1. Household Water Treatment in
Kibera, Nairobi
Ali Saikal
u4310862
Supervised by Dr Haley Jones
September 2010
A thesis submitted in part fulfilment of the degree of
Bachelor of Engineering
Department of Engineering
Australian National University
3. i
ACKNOWLEDGEMENTS
A big thank you to Haley Jones for her flexibility and open mind in supervising me with this
thesis.
I would like to thank two very helpful members of KWAHO, Francis Kage and in particular
Joshua Otieno. Their assistance has been crucial in forming a holistic understanding of
relevant aspects of study and I hope that this thesis can be of some use to them and their
organisation.
Thanks to my good friends Gabriel Nerima and Yvonne Muli, who live and have lived in
Kibera respectively. Their local insights helped give me an understanding of the receiving end
of the relevant developments.
And last but not least, I’d like to acknowledge the people of Kibera. The people of Kibera
have shaped my view of the world and so this thesis is dedicated to those people who deserve
more, yet have so much to give. Asante sana.
4. ii
ABSTRACT
Clean water is a requirement of human survival. Slum areas in developing countries are the
most deprived of this necessity and this is often attributed to government neglect. In such
situations, water treatment becomes the responsibility of the locals and due to desperate
conditions, this important practice is often overlooked resulting in wide spread water borne
disease. NGOs are often the only frontier in combating this scenario and this is commonly
attempted through implementation of appropriate household water treatment projects. This is
the case in Kibera, Nairobi – one of the most impoverished slums in the world. NGO projects
in Kibera succeed to varying degrees and it is suggested that a systems methodology be
employed by such agencies to maximise the appropriateness of implemented projects.
Through demonstration of such methodology it is deduced that solar water disinfection is an
appropriate household water treatment method for Kibera, justifying ongoing NGO
developments in this direction.
5. iii
CONTENTS
List of Figures........................................................................................................................................................v
List of Tables.........................................................................................................................................................vi
Glossary of Terms ...............................................................................................................................................vii
Chapter 1 Introduction ...................................................................................................................................1
1.1 THESIS MOTIVATION...................................................................................................................................1
1.2 THESIS INTRODUCTION...............................................................................................................................2
1.3 OBJECTIVES................................................................................................................................................3
1.4 RELEVANCE TO ENGINEERING DISCIPLINE ..................................................................................................3
1.5 SCOPE.........................................................................................................................................................3
1.6 DOCUMENT OUTLINE..................................................................................................................................3
Chapter 2 Solar Water Disinfection (SODIS) ...............................................................................................4
2.1 INTRODUCTION ..........................................................................................................................................4
2.2 METHOD OF PURIFICATION ........................................................................................................................4
2.2.1 Requirements...................................................................................................................................4
2.2.1.1 Appropriate bottle........................................................................................................................................5
2.2.1.2 Low water turbidity.....................................................................................................................................5
2.2.1.3 Appropriate climatic conditions ..................................................................................................................6
2.2.1.4 Minimal recontamination risk .....................................................................................................................6
2.3 CURRENT APPLICATION .............................................................................................................................6
2.4 LARGE SCALE IMPLEMENTATION...............................................................................................................7
2.5 SUMMARY ..................................................................................................................................................8
Chapter 3 Water in Kibera.............................................................................................................................9
3.1 INTRODUCTION ..........................................................................................................................................9
3.1.1 Kibera at a Glance ..........................................................................................................................9
3.1.2 History...........................................................................................................................................10
3.1.3 Current State .................................................................................................................................10
3.2 WATER SUPPLY .......................................................................................................................................11
3.3 WATER QUALITY.....................................................................................................................................12
3.4 LOCAL SYSTEMS OF BELIEF.....................................................................................................................13
3.5 SUMMARY................................................................................................................................................14
Chapter 4 SODIS in Kibera..........................................................................................................................15
4.1 INTRODUCTION ........................................................................................................................................15
4.2 KENYA WATER FOR HEALTH ORGANISATION (KWAHO).......................................................................15
4.3 SODIS PROJECT DEVELOPMENT..............................................................................................................15
4.3.1 SODIS Implementation in Kibera..................................................................................................16
4.3.1.1 Awareness raising in schools.....................................................................................................................16
4.3.1.2 Collaboration with community groups and key figures.............................................................................16
4.3.1.3 Door-to-door promoters.............................................................................................................................16
4.4 FOLLOW UP STUDIES................................................................................................................................17
4.4.1 KWAHO observations....................................................................................................................17
4.4.2 EAWAG Study................................................................................................................................17
4.5 DISCUSSION & KEY FINDINGS .................................................................................................................18
4.6 SUMMARY................................................................................................................................................19
Chapter 5 Appropriate Water Treatment...................................................................................................20
6. 4
5.1 INTRODUCTION ........................................................................................................................................20
5.2 REQUIREMENTS .......................................................................................................................................20
5.2.1 Method of Establishing Requirements ...........................................................................................21
5.2.2 User requirements .........................................................................................................................22
5.2.3 NGO requirements.........................................................................................................................23
5.3 APPROPRIATE METHODS OF PURIFICATION..............................................................................................24
5.3.1 SODIS Disinfection........................................................................................................................25
5.3.2 Chlorination Solution Disinfection................................................................................................26
5.3.3 Ceramic Candle Filtration ............................................................................................................28
5.3.4 BioSand Filtration.........................................................................................................................30
5.4 WATER TREATMENT METHODS VS REQUIREMENTS ..................................................................................32
5.4.1 Efficacy..........................................................................................................................................32
5.4.2 Potential faith in method ...............................................................................................................33
5.4.3 Affordable......................................................................................................................................33
5.4.4 Simple and ease of use/maintenance .............................................................................................34
5.4.5 Robust............................................................................................................................................34
5.4.6 Easy integration with household ...................................................................................................35
5.4.7 Taste ..............................................................................................................................................35
5.4.8 Low risk of theft.............................................................................................................................36
5.4.9 Networking Prospects....................................................................................................................36
5.4.10 Low associated costs.................................................................................................................37
5.4.10.1 Procurement (purchase & transport): ...................................................................................................37
5.4.10.2 Organisational set up............................................................................................................................38
5.4.10.3 Ongoing costs.......................................................................................................................................38
5.4.10.4 Implementation ....................................................................................................................................38
5.4.11 Environmental impact...............................................................................................................40
5.5 COMPARISON OF WATER TREATMENT METHODS ......................................................................................43
5.5.1 Discussion of Results.....................................................................................................................44
5.5.2 Limitations of comparison.............................................................................................................45
5.6 SUMMARY................................................................................................................................................45
Chapter 6 Women’s Group SODIS Kiosks .................................................................................................46
6.1 INTRODUCTION ........................................................................................................................................46
6.2 MOTIVATION ...........................................................................................................................................46
6.3 IMPLEMENTATION STRATEGY ..................................................................................................................46
6.4 FEASIBILITY ANALYSIS............................................................................................................................47
6.4.1 Addressing Key Issues ...................................................................................................................47
6.4.2 User Requirement Satisfaction ......................................................................................................47
6.5 SUMMARY................................................................................................................................................48
Chapter 7 Conclusions and Recommendations...........................................................................................49
7.1 INTRODUCTION ........................................................................................................................................49
7.2 CONCLUSIONS..........................................................................................................................................49
7.3 RECOMMENDATIONS................................................................................................................................49
7.4 SUMMARY................................................................................................................................................50
Appendix A – SODIS effect on water quality ...................................................................................................51
Appendix B – KWAHO’s development of SODIS in Kibera...........................................................................52
APPENDIX C – Boiling as a water treatment method in Kibera ...................................................................54
Bibliography ......................................................................................................................................................... A
7. v
List of Figures
Figure 1. Basic method of SODIS .............................................................................................4
Figure 2: a) Water circulation due to temperature profile in bottle with black bottom
b) Effect of scratching on SODIS bottle transmittance ......................................................5
Figure 3: (a) Reduction of faecal bacteria in SODIS
(b) Global solar radiation ..................................................................................................6
Figure 4. Worldwide application of SODIS ...............................................................................7
Figure 5. Nairobi street map – Kibera highlighted....................................................................9
Figure 6. Satellite image of Kibera ............................................................................................9
Figure 7. proposed assembly of Pelikan candle filtration system............................................29
Figure 8. Typical BushProof concrete biosand water filter ....................................................30
Figure 9. Score breakdown in terms of stakeholder requirement satisfaction.........................44
Figure 10. 2004-2005 KWAHO facilitated SODIS project area .............................................52
Figure 11. Current KWAHO facilitated SODIS project area ..................................................53
8. vi
List of Tables
Table 1. User requirements regarding an NGO facilitated water treatment method ..............22
Table 2. Requirements of an NGO in Kibera looking to facilitate a water treatment project .23
Table 3. Comparing Efficacies.................................................................................................33
Table 4. Comparing potential faith in each method.................................................................33
Table 5. Comparing affordability.............................................................................................33
Table 6. Scores for simple and easy use/maintenance .............................................................34
Table 7. Scores for robustness..................................................................................................35
Table 8. Integration with household scores..............................................................................35
Table 9. Comparing taste .........................................................................................................36
Table 10. Scores for risk of theft ..............................................................................................36
Table 11. Networking prospect scores .....................................................................................37
Table 12. Project cost breakdown and method scoring ...........................................................40
Table 13. Primary pollutants of each method and associated environmental impact scores ..42
Table 14. Comparison of water treatment methods VS user/NGO requirements ....................43
Table 15. Score comparison of new strategy with old against user requirements...................48
Table 16. Reduction of microorganisms in water exposed to SODIS treatment .....................51
9. vii
Glossary of Terms
EAWAG Swiss Federal Institute of Aquatic Science and Technology
Ksh Kenyan Shillings
KWAHO Kenya Water for Health Organisation
MSF Medecins Sans Frontieres
NGO Non Government Organisation
NTU Nephelometric Turbidity Units
PC Polycarbonate
PET Polyethylene terephthlate
PVC Polyvinyl chloride
SANDEC Department of Water and Sanitation in Developing Countries
UN United Nations
UNICEF United Nations Children’s Fund
UV Ultraviolet
WHO World Health Organisation
10. 1
Chapter 1 Introduction
1.1 THESIS MOTIVATION
The founding motive of this thesis is to attempt to improve the health and general wellbeing
of people who require it the most. This could also be interpreted as an intention to alleviate
poverty. Through personal travels to developing countries and a passion for learning about
and contributing to development issues in such areas, the Kibera slum of Nairobi was selected
as the subject due to the poor quality of life experienced by many of its people.
To explore avenues of potential poverty reduction it was important to understand its
substance. There are many definitions of poverty and for the sake of minimising exclusions,
the following UN definition, signed by heads of all UN agencies, was adopted due to its
holistic nature and wide acceptance:
“Fundamentally, poverty is a denial of choices and opportunities, a violation of human
dignity. It means lack of basic capacity to participate effectively in society. It means not
having enough to feed and clothe a family, not having a school or clinic to go to, not
having the land on which to grow one’s food or a job to earn one’s living, not having
access to credit. It means insecurity, powerlessness and exclusion of individuals,
households and communities. It means susceptibility to violence, and it often implies living
on marginal or fragile environments, without access to clean water or sanitation” (UNDP,
1998)
Embedded within this definition are five key elements which when lacking in society, form
the foundations of poverty: education, health, income, security and shelter. Of these elements,
the most applicable in the engineering context were deemed to be health and shelter. Potential
engineering improvements regarding these elements were then brainstormed in the context of
Kibera. It became clear that these improvements face major obstacles due to overarching
political inefficiencies within Kenya, which similar to many developing countries, pose major
constraints on foreign and local development efforts. These political forces are generally
driven by desires for political power or economic incentives. This issue has been ongoing
since many sub Saharan African countries gained independence and attempts to centralise
services have been severely hampered. Countering this deficit, some governments have been
superseded by non government organisations (NGOs) in facilitating development in many
rural and slum areas (Bratton, 1989). NGOs are formed through local willpower to help the
wider community, expressing a larger motivational capacity to alleviate poverty when
compared to politically volatile governments. In many areas, including Kenya, governments
accept this shift in responsibility and officially recognise NGOs as necessary agents for
progress (McGann, et al. 2006). It was therefore concluded that the most potentially effective
means of improving local wellbeing from an external foreign analysis was to aim efforts at the
NGO level.
11. 2
NGO initiatives in Kibera were then researched and by taking the potential scope of this thesis
and the needs of Kibera residents into account, the issue of safe drinking water and more
specifically, the implementation of household water treatment systems was considered a
worthy pursuit. After further research on several existing NGO facilitated water treatment
projects in Kibera, it became clear that there were differing NGO views as to what methods
were most appropriate and thus, developing a systems methodology behind this decision
became a goal. Research also revealed a relatively new method of water treatment which
appeared to have much potential within Kibera and exploring this became complementary
goal of this thesis.
1.2 THESIS INTRODUCTION
Four billion cases of diarrhoea occur each year worldwide and 2.2 million people die as a
result of such diseases. 88% of these cases are due to unsafe water and poor sanitation
hygiene practice, most being children under 5 years old (WHO, 2007). It is estimated that
94% of diarrhoeal cases can be prevented through modifying the environment: mainly
through increasing consumption water quality and sanitation/hygiene practice (WHO, 2007).
There is an increasing global movement towards addressing the issue of water-borne disease.
Millennium Development Goal 7 aims to: “Halve, by 2015, the proportion of people without
sustainable access to safe drinking water and basic sanitation” (UN, 2010). Efforts to reach
this goal have been institutionalised and many organisations are now implementing projects in
developing countries to address the issue of safe water consumption. In urban slums where
centralised water supply may not be of ideal quality, point-of-consumption water treatment
methods are ideal (WHO, 2002).
Kibera, located in the city of Nairobi, Kenya, is regarded by many as one of the most
impoverished slums in the world. Due to poor raw water quality, point of consumption water
treatment methods are of paramount importance and several are currently being used. One
such method is solar water disinfection (SODIS), which is currently being promoted in Kibera
by local NGO - Kenya Water for Health Organisation (KWAHO). SODIS has proven
effective in reducing water borne disease in such contexts and is appropriate due to its
simplicity and low cost. The treatment method involves filling clean and empty PET bottles
with potentially unsafe drinking water and leaving exposed to the sun for 6 hours. UV
radiation and thermal impacts disable harmful microorganisms and provide water which is
then safe for human consumption.
KWAHO has been implementing SODIS programs within Kibera since 2004 and has
continuously been monitoring and refining its implementation strategy aimed at increasing the
method’s effectiveness. One such refinement which will be explored in this thesis is a new
implementation strategy aiming to transfer management to local women’s groups (Kage,
2010).
12. 3
1.3 OBJECTIVES
The overarching objective of this thesis is to propose to NGOs in Kibera a systems
methodology which could be useful in maximising their positive impact. More specifically,
this thesis aims to demonstrate holistic selection and optimisation of NGO facilitated water
treatment projects in Kibera. With this objective in mind, the two following targets were set:
- Comprehensively determine against local requirements, the most appropriate methods
of water treatment for an NGO to implement as a large scale project in Kibera
- Holistically assess the feasibility of KWAHO’s newest strategy
1.4 RELEVANCE TO ENGINEERING DISCIPLINE
The increasingly popular notion of systems engineering explores all relevant aspects of a
system, including technical and social. Disciplines such as social sciences, management,
economics and politics all have valuable input into developments such as NGO facilitated
water treatment projects in slum areas. However, these different interests are rarely
represented on the same plane in a holistic analysis. Systems engineering analysis attempts to
understand and value all relevant aspects of a system in order to maximise its appropriateness.
Various systems engineering tools are used throughout this thesis with the intention of
reaching a comprehensive needs-based solution.
1.5 SCOPE
As mentioned previously, this thesis attempts to avoid interference with political and social
dynamics for the purpose of respecting cultural sensitivity and avoiding external obstacles.
Thus, it may be treated somewhat as a consultancy report to a local NGO, as all findings and
recommendations remain within a typical NGO’s jurisdiction and foreseeable ability. This
thesis focuses on water treatment methods with respect to Kibera, only drawing on
information from projects elsewhere where relevant to this context.
Several established methods of water treatment are explored in this thesis and exploring their
microbiological processes is necessary this level of analysis as effectiveness of these methods
will be examined on the human level – that is how well they are implemented and received
and the associated reduction of water borne disease.
1.6 DOCUMENT OUTLINE
Chapter 2 and Chapter 3 respectively introduce the subject water treatment method, solar
water disinfection; and location context Kibera – the two foundations of this thesis. Chapter 4
explores developments of NGO efforts to implement solar water disinfection in Kibera,
highlighting key issues to improvement. Chapter 5 presents and demonstrates a methodology
which local NGOs could employ to determine the most appropriate water treatment venture to
implement at a large scale. Chapter 6 draws on requirements brought up in earlier chapters to
qualitatively analyse the feasibility of a new solar water disinfection implementation strategy
in Kibera. Chapter 7 then summarises the key elements and findings of the thesis and presents
recommendations as to how these findings could be employed by prospecting NGOs.
13. 4
Chapter 2 Solar Water Disinfection (SODIS)
2.1 INTRODUCTION
Solar water disinfection (SODIS) is a somewhat new and relatively less understood than most
other common water treatment methods and so this chapter aims to introduce SODIS to
establish a firm base of understanding as it is further analysed throughout later chapters. Put
shortly, the simplicity of SODIS makes it a viable water purification method for warm areas
with abundant sunlight.
The SODIS method of purification was originally discovered in 1980 by Professor Aftim
Acra at the American University of Beirut. In 1991, the Department of Water and Sanitation
in Developing Countries (SANDEC) at the Swiss Federal Institute for Environmental Science
and Technology (EAWAG) initiated further research and development and began
implementing SODIS projects in developing countries. Since then, SODIS has gathered more
publicity and support and is endorsed by the World Health Organisation, UNICEF and the
Red Cross (EAWAG, 2010). EAWAG are the institutional frontier of SODIS projects and are
currently coordinating projects in 33 developing countries through local organizations
(EAWAG, 2008). For the purpose of simplicity, we shall henceforth refer to the conglomerate
of SANDEC and EAWAG as EAWAG.
Table 16 in Appendix A shows SODIS reduction of microorganisms found most commonly in
raw water in developing countries.
2.2 METHOD OF PURIFICATION
The basic SODIS method of treating water is simple and easily illustrated diagrammatically
such as the following from the SODIS website:
Figure 1. basic method of SODIS (EAWAG, 2010)
2.2.1 Requirements
SODIS is widely applicable but does have conditional requirements which contribute to its
effectiveness and following sections outline these.
14. 5
2.2.1.1 Appropriate bottle
Commercially made polyethylene terephthalate (PET) bottles (labels removed) are
recommended over glass or other clear plastic bottles for several reasons:
- They have become popular worldwide over recent times and are mass
produced, easily available and relatively cheap
- They are lighter and less likely to break compared to glass bottles
- Compared to other bottle materials (eg, PC - polycarbonates, PVC - Polyvinyl
chloride) PET bottles have thinner walls and allow more UV transmission. The
material properties also allow for superior UV transmission (The Water
School, 2009)
- Other plastics have associated risks of chemical leaching into the contained
water but this risk has been proven negligible with PET bottles given their use
within SODIS (Schmid, et al. 2008)
Assuming suitable climatic conditions, water with turbidity less than 30 NTU (explained in
following section) can be disinfected effectively up to approximately 10cm deep (EAWAG,
2010). For this reason, bottles of 2L capacity or less are to be used.
Bottles can be made more effective for SODIS by colouring the bottom black. This generates
more heat and creates a vertical temperature gradient within the bottle, causing circulation and
thus improving the rate of disinfection (EAWAG, 2010) as shown in Figure 2a.
Figure 2: a) water circulation due to temperature profile in bottle with black bottom (created in MS Paint)
b) Effect of scratching on SODIS bottle transmittance (Wegelin, et al. 2001)
EAWAG have conducted tests to show that if SODIS bottles are used each day as described,
the only factor degrading the effectiveness of the method is the scratching of the bottle’s
surface, reducing UV transmittance (Wegelin, et al. 2001). As this depends on the frequency
and nature of use, there are no specific guidelines regarding lifespan except that bottles should
be discarded once transmittance has impaired the ability to read writing through the bottle
(EAWAG, 2010). Various reports on past projects divulge that this generally occurs after
several months.
2.2.1.2 Low water turbidity
Turbidity is the concentration of suspended solids in the water and is measured in
(a)
15. 6
Nephelometric Turbidity Units (NTU). Tests have shown that to allow for sufficient UV
penetration in suitable climatic conditions, a water turbidity of less than 30 NTU is required
(EAWAG, 2010). If water exceeds this level of turbidity, it can be pre-treated using various
methods (eg, flocculation/sedimentation, filtration) until ideal turbidity is reached. Turbidity
can be roughly approximated by placing the bottle full of raw water on a newspaper – if
headlines are readable then the turbidity is less than 30 NTU and the water can be effectively
treated with SODIS (EAWA, 2002).
2.2.1.3 Appropriate climatic conditions
The effectiveness of SODIS depends on solar intensity and temperature, both of which are
heavily determined by global position. SODIS is effective for areas within a 35º latitude
window with respect to the equator (EAWAG, 2002), as this area is subject to higher solar
exposure.
(a) (b)
Figure 3: (a) Reduction of faecal bacteria in SODIS (EAWAG, 2002)
(b) Global solar radiation (modified from: EAWAG, 2002)
If there is cloud cover, SODIS can still be used to treat water but it must remain exposed to
the sky for 12 hrs of light or 2 full days to accumulate sufficient solar exposure (EAWAG,
2002).
2.2.1.4 Minimal recontamination risk
EAWAG suggests that SODIS treated water should be stored in its bottle and for no longer
than 2 days – this is to prevent microorganism regrowth (EAWAG, 2002).
2.3 CURRENT APPLICATION
EAWAG has assumed the responsibility as the largest global promoter of SODIS and takes to
role of supplying governments, NGOs and international organisations with expert knowledge,
training material and practical support such as links to funding agencies, etc. The latest global
SODIS update from the 2008 SODIS newsletter stated that SODIS projects were running in
33 countries around the world and have experienced reductions of water borne disease of 20-
50% (EAWAG, 2008).
16. 7
Figure 4. Worldwide application of SODIS (EAWAG, 2008)
2.4 LARGE SCALE IMPLEMENTATION
Before the commencement of an NGO facilitated large scale implementation of SODIS in a
developing area, it must be deemed feasible in order to gain funding from potential donors.
For this reason, pilot projects are instrumental in examining how effective SODIS can be in a
given area with respect to:
- Climatic conditions
- Resulting diarrhoea reduction rates
- Local social requirements
If a pilot project proves effective, then a large scale implementation may be feasible. Whether
or not it eventuates from here generally but not necessarily depends on the ability and
willingness of facilitating agencies to collaborate with international SODIS promoters,
EAWAG. If this takes place, EAWAG and the local agency exchange information and design
an appropriate project implementation strategy (EAWAG, 2008).
There are two main avenues through which SODIS has been effectively scaled-up in
developing countries (Gurung, et al. 2009):
- government agencies
- local NGOs
The effective scaling-up of SODIS through government agencies demands more resources
and time as it may require more localised analysis which could lead to various different
implementation strategies being employed in different areas. Despite this drawback,
government facilitated projects can have a wider reach and consequently, larger positive
health impacts for more people. Although NGOs reach a smaller group of people, there are
many impoverished areas around the world where government presence is minimal and NGOs
are the primary holders of local information useful in implementing such projects. Under
these circumstances, it is logical that the NGOs facilitate SODIS projects.
17. 8
NGO implemented projects have a tendency to phase out once funding is all spent (Gurung, et
al. 2009). It is therefore advisable that funded NGOs implementing SODIS projects should
devise long term plans to transfer ownership of the project to the communities they serve in
order to maintain sustainable SODIS use.
2.5 SUMMARY
The SODIS method of water purification has been widely endorsed and its application is on
the increase. It’s low cost and simplicity make it an ideal and effective method for warm areas
subject to high UV exposure. SODIS is being implemented through various organisational
arrangements and strategies are best analysed case specifically depending on these potential
arrangements.
18. 9
Chapter 3 Water in Kibera
3.1 INTRODUCTION
This chapter introduces the subject area, Kibera, focussing on aspects related to human water
consumption.
3.1.1 Kibera at a Glance
Located about 7km South West of Nairobi city, Kibera is renowned of its poor living
conditions and has been dubbed one of the most impoverished slums in the world by many
publications (COHRE, et al. 2007). Kibera is approximately 550acres (2.3km²) and no
comprehensive census has been conducted in Kibera but population estimates range between
0.4 and 1.2 million (COHRE, et al. 2007; UNDP, 2006).
Figure 5. Nairobi street map – Kibera highlighted (Nairobi street map 2010)
Figure 6. Satellite image of Kibera (Kibera satellite image 2005)
19. 10
3.1.2 History1
Kibera was originally dense forest land but in between 1912 to 1920 (varying historical
information), it was allocated by the British colonial government as a settlement for the
Nubian tribe in return for their service in the British army during the First World War.
Nubians originally came from northern Sudan and the name “Kibera” is Nubian for forest or
jungle. In an attempt to reduce their debt to the Nubians, the British colonial government
allowed the settlements to grow informally. Under British government law, Kenyan tribes
were each allocated areas of ‘native reserve’ within Kenya which they claimed as their own
land from then on. The Nubian tribe however, was not Kenyan and so was allocated land
which was not classified as any other tribe’s ‘native reserve’ but they did not have the right to
claim it as their own – deeming them squatters.
3.1.3 Current State
Following Kenya’s independence in 1963, various forms of housing were made illegal,
including those which were not based on official land tenure. The residents of Kibera were
thus rendered illegal squatters and Kibera was excluded from all municipal services. Nubian
squatters, informally claimed land as their own and rented it out for relatively cheap rates and
as a result, poor people from all over Kenya migrated to Kibera in search of work close to the
capital, consequently forming what is now one of the most dense and impoverished slums in
the world.
Currently with a population of 0.4 - 1.2 million (UNDP, 2006), Kibera is now renowned as
one of the most impoverished slums in the world, with between 40-49% of workers earning
below the poverty line of 2000Ksh/month (MPND, 2003). The average house size is
approximately 3mx3m and accommodates 5 residents (CSG Kibera, 2010; Women for
Women in Africa, 2010). Major reasons for this sprout from the general lack of government
involvement in the area, meaning no municipal infrastructure exists and the few services
available, including: schools, clinics and utility supply are privately run (The Economist,
2007).
Kibera’s very high population density, lack of infrastructure and that it contains a mix of
different tribes in very close quarters are a major cause of inter tribal conflict, somewhat
inhibiting social cohesion. This is evidenced by historical records of water shortages resulting
in riots and deaths (IRIN, 2001; Makori, 2007)
In terms of population dynamics Kibera is highly volatile for several main reasons (KWAHO,
2008 (2)):
- People frequently move from village to village searching for work
1
Information gathered from Amnesty International (2009) and Hagen (2010)
20. 11
opportunities
- Lack of legal land tenure makes renter-landlord relationships fragile, often
leading to evictions.
- Constantly rising population from people migrating to Kibera from poor rural
areas in search of a better life.
The highly dynamic nature of Kibera also poses limitations to social cohesion, further
limiting the ability of communities to improve their conditions.
These factors combined have produced a state of desperation where crime is common,
disease is rife, medical attention is scarce, human waste lines streets, work hours are long and
with insufficient reward – a situation so dire that Kibera is now perceived as a reference of
poor living conditions by international development agencies – an example of what to avoid.
These conditions are represented through several estimated statistics:
- 80% youth unemployment (The People of Kibera, 2010)
- 20% of children do not live to 5 years of age (UNDP, 2006)
- Rates of bloody diarrhoeal infection are 3 times the national average (UNDP, 2006)
- 15% occurrence of HIV/AIDS, twice the national average (MSF, 2005)
- 1/3 of children do not go to school causing low literacy rates (Erulkar, et al. 2007)
Perhaps the largest direct physical cause of poor health in Kibera is the consumption of
contaminated water supply, which is introduced in the next two sections.
3.2 WATER SUPPLY
68% of Kibera residents rely on local water kiosks which are positioned such that on average,
it is a 40m distance to the closest kiosk (COHRE, et al. 2007). Kiosks are run within Kibera,
supplying water from municipal water lines owned by the Nairobi City Council (NCC) and
managed by the Nairobi Water and Sewerage Company (NWSC). In 2006, 98% of the 650
water kiosks in operation in Kibera were run by private vendors and the rest by community
based organisations (CBO) or NGOs (IRIN, 2010). Kiosks sell water to locals for a usual fee
of 2-3Kshs per 20L jerry can and this price can go up to 20Kshs in times of shortage
(COHRE, et al. 2007). Shortages occur frequently due to:
- Connection pipes failing or being broken by water cartels trying to eliminate
market competition. CBO or NGO connection pipes are particularly
vulnerable to this as they often try to sell at a cheaper price, lowering the
revenue of their generally poorer private competitors whose livelihoods
depend on water sales (Mathenge, 2009)
- Occasional large diversions elsewhere such as the annual Nairobi Show
(COHRE, et al. 2007)
- The nation-wide lack of water (Momanyi, et al. 2005)
Water prices at private kiosk outlets in Kibera are high compared to other areas of Kenya due
to large costs associated with running the kiosks – approximately 75 000Ksh for construction
21. 12
with up to 20 000Ksh for associated bribes to officials (COHRE, et al. 2007) and the ongoing
costs of 10Ksh/m³ charged by NWSC to informal settlement kiosks (Mwega, 2008). A 2007
survey showed the average monthly household expenditure on water for each of village in
Kibera and the average of these was approximately 860Ksh/household/month (COHRE, et al.
2007). The high prices add another dimension to the difficulty residents face in acquiring
sufficient quantities of water.
19% of Kibera’s water is supplied through direct connections to NCC water lines via
household connections and yard taps and to a lesser privately operated wells and a borehole
(COHRE, et al. 2007).
3.3 WATER QUALITY
Kiosk operators usually connect to NCC supply via narrow PVC or old galvanised steel pipes
which are frequently subject to leaks and as they are often running in open gutters to be out of
the way and they are consequently subject to contamination by surrounding sewerage matter
(KWAHO, 2008 (1)). A study conducted by C. Obuya, a senior laboratory technologist with
the Ministry of Water and Irrigation at the Central Water-testing lab, showed that water
running through the Nairobi City Council lines was of high quality but water from most of
the pipes, taps and reservoirs within Kibera were contaminated with bacteria, especially
E.coli (Waititu, 2008). Also, the reduction of diarrhoea rates after water treatment methods
further affirms the contamination of raw water (KWAHO, 2008(2)). The resulting situation is
a vast majority of Kibera residents relying on unsafe water supply.
The susceptibility of water to diarrhoeal diseases heavily depends on its total coliform
content and Enterotoxigenic Escherichia coli (e.coli) content (MIT, 2008). Total coliform
levels in water illustrate the abundance of fecal bacteria – the most common type of coliform
being E.coli (Ashbolt, 2001). E.coli is the main cause of diarrhea worldwide and originates
within the gut of warm blooded animals (WHO, 2010). It can be measured directly but this is
a difficult process. An easier method involves measuring the colony-forming-units (CFU) in
water, which represents the total bacteria population present (Ashbolt, 2001). Determining
the CFU does not identify how much of the bacteria is actually e.coli but as we are interested
in water quality in only Kibera, we can assume the ratio of e.coli to total bacteria will remain
somewhat constant between measurements as reasons for contamination remain the same
(pipes exposed to sewerage). Thus, for the purposes of acquiring more data and reaching a
comprehensive comparison of water purification methods in Chapter 5, we will henceforth
use CFU as our indicator of water quality. To put this into local context, it was mentioned
previously that high levels of e.coli have been noticed in water output by Kibera kiosks and
this was verified in 2006 by EAWAG water quality tests. Categorised data presented in this
study (Graf, et al, 2008) was interpolated to reveal that kiosk output water contained
approximately 29CFU/100mL and water sampled from household storages contained
approximately 97CFU/100mL. The increase of bacteria in household water can be linked to
22. 13
poor hygiene practices such as residents contacting the water with unwashed hands, etc.
Turbidity reflects the amount of sediment particles present in water and this is important as
bacteria often attach to these particles and become somewhat more resilient against treatment
methods (Go´mez-Couso, et al. 2009). Water output from Kibera kiosks is consistently of
very low turbidity and although no published data was available on this, local water treatment
expert Otieno J. (2010) conservatively estimates average water output from kiosks at less
than <3NTU. Turbidity of this magnitude poses relatively negligible health risks to
consumers on its own but may slightly heighten the risk of bacterial contamination – an issue
to be addressed by treatment methods explored later in this chapter.
3.4 LOCAL SYSTEMS OF BELIEF
Since our topic of water purification involves methods developed in the Western world being
employed in Kibera, it is important to understand the differences between Western and local
perspectives or beliefs regarding scientific processes. In 1997, Olugbemiro J., currently a
professor at the Open University of Nigeria, produced an article - School science and the
development of scientific culture: a review of contemporary science education in Africa,
shedding light on this dichotomy. Historically, the development of Western society has been
heavily influenced by scientific discoveries and advancements and as a result, science has
been praised in the developed world as a necessary tool for progress. The value of science in
Western society is so deeply rooted in our history and conditioning that we use it to
understand the world and justify what we do in it. On the other hand, African cultures
historically developed and justified their surroundings on anthropomorphic beliefs –
assigning human characteristics to elements of nature. Such belief systems remain present in
some African cultures and are apparent in various forms such as belief in witchcraft. The
difference in the two foundations of belief systems can be used to explain what many
Westerners would call “lack of knowledge” amongst Africans facing systems introduced by
the developed world, discovered through Western science.
This theory can be used to explain why some people of Kibera are not using water treatment
processes to their full effective potential - most of these treatment systems were discovered
through Western science, and are not as easily justified by locals with little understanding of
Western science. An example of this can be seen in the EAWAG/KWAHO facilitated Kibera
SODIS follow up study in 2006, where mothers were asked as series of questions, one being:
“Can young children get diarrhoea for supernatural reasons such as witchcraft or breaking the
norms?”. Results were recorded in the form; 1) definitely not, 2) probably not, 3) maybe, 4)
yes and 5) definitely yes. From a sample size of 498, the mean result was 2.66 with a
standard deviation of 1.55 (Graf, et al, 2008), illustrating a moderate presence of beliefs
incompatible with Western science beliefs.
23. 14
Amongst other things, Western science explains physical yet unseen things in our
environment – eg, microbiology, physics, chemistry, etc. Western scientific history and
standard education programs have built our faiths in these sciences of the unseen physical
world. Without much of this conditioning, it is conceivable that some Africans may base their
explanations of physical phenomena purely based on what they can see and have heard
gathered from their anthropomorphic history. To contextualise, a common perception in parts
of Kenya is that “clear water is clean water” (Baffery, 2005), affirming this hypothesis.
Olugbemiro also pointed out that in African areas where there is a strong Western presence,
some locals interpret this as Western worldviews being imposed over theirs and react with
some degree of distaste. Such reactions have been observed on a small level in Kibera by
some NGOs affiliated with international agencies (Momanyi, et al. 2005). This distaste or
impatience may also be attributed to a lack of faith in institutions (also introduced to Africa
by the Western world). Such mentality is also understandable considering Kibera’s history of
government neglect.
3.5 SUMMARY
This chapter has introduced Kibera, the subject area of this thesis, focussing on the poor
water conditions which locals face. It has been revealed that neither the relevant government
authorities (NWSC) nor the Kibera kiosk operators have assumed responsibility of assuring
quality water output, thus implying that the only remaining measure to achieving safe water
consumption in Kibera is by placing the responsibility on the locals themselves. This paves
the road for the following chapters regarding water treatment methods and to address one
major hurdle in achieving such developments, this chapter has also provided a background on
faith systems within Kibera, highlighting how they may be relevant in this context.
24. 15
Chapter 4 SODIS in Kibera
4.1 INTRODUCTION
This chapter introduces the only NGO facilitated SODIS project in Kibera (Otieno, 2010),
which becomes a primary focus of subsequent chapters. It outlines developments throughout
KWAHO’s implementation of this project in Kibera and highlights lessons learnt to provide a
platform from which following chapters further explore.
4.2 KENYA WATER FOR HEALTH ORGANISATION (KWAHO)
Kenya Water for Health Organisation is currently the only NGO implementing SODIS in
Kibera. Founded in 1976 by the National Council of Women in Kenya, KWAHO’s mission
is:
“…to offer partnership to disadvantaged communities to improve their social and
economic standards by facilitating the provision of safe water, hygienic sanitation,
management of sustainable environment and promotion of income generating
initiatives.” (KWAHO, 2010)
SODIS is KWAHO’s primary initiative aimed at improving point-of-consumption water
quality.
4.3 SODIS PROJECT DEVELOPMENT
In 1995, a one year SODIS project was trialled amongst Maasai children in rural Kenya and
experienced positive results (Conroy, et al. 1996). Years later, this inspired KWAHO to
assess the feasibility of such a project in Kibera by conducting a preliminary participatory
community needs analysis (KWAHO, 2008 (2)), which concluded the following (Baffrey,
2005):
- The community requires access to safe drinking water
- Water borne disease is common
- Pipes connecting water kiosks to municipal water supply often leak or burst,
contaminating water being sold in Kibera
- Community leaders recognise the importance of water quality
- Locals are somewhat willing to participate in a water treatment project
On realising the potential of a SODIS project in Kibera, collaboration was established
between KWAHO and EAWAG through which expert knowledge was transferred regarding
the SODIS method and implementation strategies. In addition, EAWAG assisted in
connecting KWAHO with donating agencies including Swiss Rotary Clubs, the government
of Luxembourg and the Solaqua Foundation (KWAHO, 2010), providing KWAHO with the
capacity to introduce SODIS to Kibera on a large scale.
25. 16
4.3.1 SODIS Implementation in Kibera1
In 2004, KWAHO initiated its SODIS project aimed at reaching 20 000 people in the village
of Makina2
(Baffrey, 2005) and KWAHO now distributes bottles to approximately 65 000
households over 7 villages of Kibera3
, equating to over 300 000 residents (Otieno 2010).
Throughout implementation, KWAHO has emphasised the importance of safe hygiene
practice alongside safe water treatment as the two are highly integrated regarding risk of
contracting water borne disease.
The only materials required for residents to use the SODIS method are PET bottles and
KWAHO purchases 1.5L PET bottles from bottle manufacturers and hotels in Nairobi for
12Ksh each and sells them in Kibera for 10Ksh, absorbing 2Ksh per bottle – a subsidy
covered by KWAHO’s external funding groups (Kage, 2010). KWAHO’s implementation
strategy revolves heavily around working within the community and avoids acting as an
external agent. This is evident in their various strategy components outlined below.
4.3.1.1 Awareness raising in schools
Schools have been specifically targeted for spreading awareness of SODIS. KWAHO has
recorded that it is common that women and girls are generally responsible for collecting of
household water in Kibera and targeting schools was one of the only ways to reach these girls
whilst respecting cultural norms. In addition, it was known that children are most susceptible
to water borne disease, further justifying the benefits of school-based implementation.
KWAHO facilitated short presentations in which they demonstrated the SODIS method and
safe hygiene practices and distributed relevant leaflets for children to take home.
4.3.1.2 Collaboration with community groups and key figures
KWAHO regularly facilitates and participates in community meetings and events, attempting
to maintain higher level interest and support. Key figures, community groups and other
cornerstones of community such as churches and medical centres are valuable to KWAHO as
they have a specialised local knowledge of issues regarding water sanitation and treatment.
They possess a more accurate view of local perceptions towards the method and this assists
KWAHO in locally tailoring its approach if need be.
4.3.1.3 Door-to-door promoters
KWAHO employs and trains locals to individually promote SODIS on a household level in
their respective areas. These promoters are also the primary means of distributing bottles,
receiving payment and creating loan accounts. They regularly visit households and attempt to
explain the benefits of SODIS treatment. This is done on a personal level in the hope that
residents may ask whatever questions they like about SODIS and not feel patronised or
embarrassed. This personal level of interaction also allows KWAHO to obtain more accurate
1
Unless otherwise stated, all information in this section was derived from (KWAHO, 2008)
2
See Figure 10 (Appendix B) for a map of initial project area
3
See Figure 11 (Appendix B) for a map of current project area
26. 17
feedback.
4.4 FOLLOW UP STUDIES
For a project implemented in such a volatile area, relatively little can be predicted about how
things will eventuate and so follow up studies are crucial in pointing out issues which must be
addressed to maximise success. The two most comprehensive available sources of this
project’s issues are KWAHO’s set of ongoing observations and a study conducted in 2006 by
a group of EAWAG consultants.
In 2004 KWAHO recorded a SODIS uptake rate of 89% (Baffrey, 2005). However in 2006,
an EAWAG survey revealed that 23% of mothers in SODIS exposed areas still fed their
children (below the age of 5) untreated water (Graf, et al. 2008). This apparent decline in
uptake may be attributed to several factors, some of which are presented by KWAHO and
EAWAG below.
4.4.1 KWAHO observations1
- The rapidly changing population dynamics (3.1.3) means that KWAHO must
constantly promote to newcomers to ensure that SODIS does not phase out
- Some residents become confused when exposed to competing water treatment
methods
- Targeting women is advantageous as they are generally the ones responsible
for supplying household water in Kibera cultural norms
- The level of social skills (personality, leadership, marketing and
communication skills) and desire to help of the door-to-door promoters greatly
correlate with the project’s success
- There remains doubt amongst some residents that “water could be cleaned by
the sun” (Baffrey, 2005)
- KWAHO’s resources are insufficient to keep up with the demand for bottles
- Some users of SODIS have created debts yet refuse to pay them off. Their
reasoning for this is that KWAHO is an NGO and the purpose of NGOs in
their mind is to ‘give to the people’ and not take (Kage, 2010)
- Strong collaboration with other agencies such as government, funding
agencies and local groups is crucial for success
4.4.2 EAWAG Study
In 2006, a group of EAWAG consultants engaged local door-to-door promoters from
KWAHO to conduct interviews with 500 houses in SODIS exposed areas of Kibera with
children below the age of 5, to gain an insight into local perspectives on SODIS and
1
Unless otherwise stated, all information in this section was derived from (KWAHO, 2008(2))
27. 18
waterborne disease (Graf, et al, 2008). The subsequent report (Graf, et al. 2008) explored
several belief variables regarding safe water consumption: understanding of risk, severity and
causes of young children getting diarrhoea and also understanding/norms of water sanitation.
Results showed that there were two main driving factors of SODIS uptake: the level of
understanding of microbiological causes of diarrhoea and perceived social norms.
Additionally, the study also conducted water tests on kiosk output water, water in household
jerry cans and the same water after it had been treated through SODIS. Results showed water
qualities of: 29CFU/100mL, 97CFU/100mL and 3 CFU/100mL respectively, indicating that
hygiene practices were causing decreased water quality within the households and that
SODIS was capable of drastically improving this water quality with a CFU reduction of
96.91% (100(1-[3CFU/100mL]/[97CFU/100mL]). This study also found that households
regularly using SODIS had 42% less cases of children diarrhoea compared to households
where children were allowed to consumed raw water, further affirming the efficacy of the
SODIS method.
4.5 DISCUSSION & KEY FINDINGS
Observations on the SODIS project in Kibera have highlighted areas of improvement within
the organisation’s operations and also some local belief issues which appear to be dampening
uptake of the method. The latter somewhat affirms what was hypothesised in 3.4, where it
was postulated that some Africans understand physical phenomena inherently differently to
Western understandings, which have been built on a centuries of scientific rigor. Without a
firm understanding of the microbiological treatment process, SODIS may be perceived as a
peculiar foreign practice not worth knowing. Some of KWAHO’s strategies serve to convert
this mentality by integrating SODIS within society through various subtle forms which aim to
increase its social acceptance. If this is effectively done, then it is reasonable to assume that
over time, SODIS will be accepted as a cultural norm and those who once ignored the method
would feel more social pressure towards it.
One of KWAHOs strategies focuses on collaboration with key figures in communities as
these people have more ability to act as distillers of information due to their more
participatory role in culture and belief developments. Many locals may look up to these key
figures as role models and maintainers of cultural wellbeing and this gives these key figures a
unique ability to develop local beliefs to incorporate knowledge developed elsewhere.
The school implementation sub-strategy is also instrumental in developing faith systems
towards SODIS. As children are the creators of the future, a firm understanding of the
advantages and scientific processes of water treatment will presumably guide local beliefs to
embrace and adopt water treatment methods as part of their own culture. As the children
grow up with this knowledge and continuously apply it, the understanding of water treatment
benefits will presumably become inherent within culture. This is could be a potential catalyst
28. 19
for local culture to no longer view systems established through Western science with
scepticism but to embrace it as their own.
KWAHO also acknowledged the important role of women in water treatment projects, given
that they are generally responsible for gathering water for the household, not to mention
feeding young children.
NOTE:
An additional issue not mentioned in either of the studies mentioned in this chapter was
introduced in 2.4, where the suggestion made was that NGOs operating their projects off
finite funding should design a plan in which they can transfer ownership of the project to the
local community. KWAHO is currently in the process of phasing in such a strategy, which
acts to heavily involve women and mitigate issues encountered with their traditional
approach. This will be discussed further in Chapter 6.
4.6 SUMMARY
After formally introducing KWAHO, this chapter outlined its strategy of implementing
SODIS in Kibera, highlighting strengths and weaknesses discovered by different follow up
studies. It was justified through various figures and explanations regarding belief systems that
KWAHO’s close involvement with the community has been a crucial factor in its success
thus far. Despite the promising results of KWAHO’s implementation of this project, the
transferring of project ownership to the community is increasingly important as funds are not
infinite. This chapter has provided relevant background for the next two chapters to base their
analysis on.
29. 20
Chapter 5 Appropriate Water Treatment
5.1 INTRODUCTION
As established in Chapter 3, the people of Kibera are not supplied with quality-guaranteed
water and so household water treatment has much to offer. In treating water and reducing risk
of disease, families are able to save money which would have otherwise gone towards
medical treatment, giving them more to money for food and other important necessities.
There is little governance over kiosk water quality and studies mentioned in 3.3 have shown
that the average quality of water sold at kiosks is approximately 29CFU/100mL (Graf, et al
2008), suggesting the need for treatment. Water treatment becomes the responsibility of the
residents and several methods are available within Kenya which satisfy resident and
facilitating NGO requirements in various ways. This chapter aims to comprehensively assess
the feasibilities of several water treatment methods and could be useful to potential
implementing agencies within Kibera. The methodology employed is outlined as follows:
- Establishment of user and NGO requirements
- Research based selection of appropriate water treatment methods
- Maximise understanding of the selected systems
- Analyse these systems in terms of how well they meet requirements
- Compare methods to determine the most appropriate
5.2 REQUIREMENTS
The driving requirement is that a household can treat drinking water for its residents to a high
standard. The World Health Organisation’s 3rd
edition of Water Quality: Guidelines,
Standards and Health (2004) suggests that water quality in developing countries is not
judged numerically against set standards but is instead assessed through a risk-benefit
approach, as it is often impossible to achieve modern standards given their conditions.
Complying with this, we shall gauge each method of purification relatively, by assessing their
relative and not absolute benefits. For the sake of establishing numerical context,
<10CFU/100mL is considered “low risk” water for consumption (WHO, 2004) and therefore
all methods explored must satisfy this specification. If treated water quality data is
unavailable, the reduction in diarrhoeal diseases amongst users can be used as an alternative
indicator in determining method efficacy. This is based on the assumption that the quality of
water consumed directly correlates with probability of contracting water borne disease.
WHO recommends a daily minimum of 7.5 L of water for each person’s consumption and
food related water uses (Howard, 2003). However, due to price and availability constraints,
an average household in Kibera uses much less than this for drinking and eating purposes. No
published statistics could be found regarding the actual consumption of water in Kibera but
30. 21
through discussions with Otieno J. (2010) and Nerima G. (2010) both of which have
extensive history in Kibera, an average consumption of 1L per person per day was agreed
upon. It must be noted that water used in food preparation is often untreated but this was
deemed acceptable as it is generally used in boiling foods, in which the boiling process
purifies the water. Thus, given that an average household consists of 5 people, the average
consumption of water per house is 5L/day (or 1825L/yr) and as we are analysing water
quality and not quantity, we shall assess water treatment methods based on their ability to
effectively treat this amount.
To assess the feasibility of various NGO-implemented purification methods in Kibera, we
must compile a set of criteria to which their success depends on. The two main stakeholders
are the users and the facilitating NGO and each have a separate set of criteria which represent
their relevant interests. The importance of each criterion was allocated a score between 1 – 5,
depicting the magnitude of their associated risk (5 being most important).
5.2.1 Method of Establishing Requirements
Realistically there are many social aspects which affect user and NGO decisions in Kibera
but all of these cannot be documented in this thesis due to the complexity and scale of such
an endeavour. The following list of requirements and their associated importance are based
on my own perceptions of local and NGO attitudes. I believe that through my research, and
experience and collaboration with locals and NGOs in the area, my perspectives are
somewhat representative of local conditions but it is important to note that this analysis is
limited by its lack of public input. A more holistic study would survey communities and
various NGOs in the area but given my position, this was deemed out of the scope of this
thesis. My own perceptions of user and NGO requirements in Kibera are obviously not as
well rounded as a local’s and so for lack of a thorough public participation system, I
collaborated iteratively with small parties from both relevant groups in the derivation of the
set of requirements:
- Joshua Otieno (KWAHO’s Kibera SODIS project coordinator)
- Francis Kage (KWAHO Programs Officer SODIS Reference Centre)
- Gabriel Nerima (teacher at the School of Hope, Gatwekera, Kibera)
- Yvonne Muli (former Kibera resident – currently studying at United States
International University, Nairobi)
NOTE:
NGOs conducting community needs assessments such as this often do so via employees
representing the organisation who approach individuals and ask a set of questions.
Results may be biased due to the following limitations:
o Some questions may be considered personal and this may evoke a
biased response. This limitation was identified in the 2006 EAWAG
follow up study in Kibera, in which KWAHO interviewers asked
31. 22
mothers questions regarding hygiene practices involving their
children. Concern was mentioned that mothers may have been too
embarrassed to truthfully converse with the interviewer on such an
issue, which could give them the appearance of a non-caring mother -
an undesirable image (Graf, et al. 2008).
o As mentioned in 3.4, some locals express distaste towards NGOs and
this could lead them to respond untruthfully to intentionally undermine
NGO operations.
These biases are not present in our set of requirements as the locals involved in its
development have been personal acquaintances of mine for several years.
5.2.2 User requirements
A solid understanding of local needs are of paramount importance in any project aimed at
providing goods or services on a large scale. In the context of NGO facilitated water
treatment methods in Kibera, such understanding would be acquired through large scale
social involvement between NGO workers and locals. As mentioned previously, locals may
have negative perceptions of NGO institutions and so it is important that the NGO
approaches this phase in a non-confronting and welcoming manner to ensure that results are
as representative as possible. Table 1 below presents the set of user requirements deduced by
myself in collaboration with the parties mentioned above. It should not be perceived as a
representative list but as a preliminary guideline which may be modified and expanded on,
should an NGO wish to assess the feasibility of various water treatment projects.
Table 1. User requirements regarding an NGO facilitated water treatment method
Requirement Description Importance
Efficacy It is important that the method effectively and consistently purifies 5L/day
of water for an average household. This is assuming that the water stored in
households, which is what we aim to treat, is of 97CFU/100mL and <3NTU
(3.3).
5
Potential faith in
method
In areas such as Kibera, where many are not educated, scientific
explanations are less understood and so for a user to adopt a water treatment
method without fully understanding the associated microbiological
processes, there must be faith in it. Several factors may influence the faith a
resident has in a particular method:
- Appearance of device (people would select a machine
manufactured filter over an old bottle)
- Information transfer (social marketing)
- Popularity / social trends
- Existing beliefs of water treatment (3.4)
This is important because if the users do not believe the method will work,
they simply will not use it. Thus, the faith in a method can be quantified by
observing its uptake and continuation rate in projects nearby which have
been implemented well.
5
32. 23
Affordable Obviously users want to pay the least amount of money to purify their
water. This is particularly important in Kibera given the abundance of poor
people. Also, the distribution of payments over time is an important factor –
a method which costs 100Ksh once a year is less affordable than a method
costing 25Ksh every 3 months as residents may not have large amounts of
money at any one time. To provide some context to affordability, as was
stated in 3.1.3, 40-49% of incomes in Kibera are less than 2000Ksh/month
and it is reasonable to assume that these lower income earners are in greatest
need of improved water quality.
The risk associated with affordability is that it will not be popular with
users. This risk is less than that of ineffective water treatment.
4
Simple and easy to
use/maintain
It is desirable that the system is easy to operate/maintain as people will not
adopt a system which requires what they consider to be too much work.
Also, it is important that the method is simple enough to allow for effective
information transfer. Some poorer families may leave children at home
whilst the adults are out working in the day so methods which can be easily
practiced by children are particularly beneficial.
If the users do not fully understand the method, they may perform it
incorrectly and consequently insufficiently treating their water. The
magnitude of this risk makes this requirement of high importance.
4
Robust Users want a system which will not fail. For all methods explored in this
section, failure is obvious and will be noticed by the users. Thus, the result
of failure is replacement or discontinuance of the method.
3
Easy integration
with household
For the sake of convenience in such small houses, it is desirable that the
method does not encroach on other daily activities.
2
Taste Past water purification projects around the world have shown that user
uptake is lower for methods which alter the taste of the water.
2
Low risk of theft Another factor considered was the vulnerability of the purifying device to
theft. Thievery is commonplace in Kibera and any device which is easily
accessible and can be sold for value is potentially at risk.
1
5.2.3 NGO requirements
The set of NGO requirements listed in Table 2 were deduced through research of NGO needs
assessments of various projects and through collaboration with KWAHO members. It is
important to note that NGOs may not share the same goals and abilities and that this is a
rough approximation of requirements of a typical NGO in Kibera.
Table 2. Requirements of an NGO in Kibera looking to facilitate a water treatment project
Requirement Description Importance
Networking
prospects
Various methods are being promoted by international agencies which often
provide information and sometimes funding for projects in developing
countries. The Kenya Ministry of Water Resources Management and
5
33. 24
Development are also potential providers of networking and financial
support to NGOs. Through collaborating with other agencies, a local NGO
will increase its experience and credibility as a capable organization, paving
the way for further developments such as up-scaling existing projects and
diversifying their approaches to helping people.
To achieve this, an NGO will usually communicate with these agencies with
a project proposal and request for assistance. This requirement is measured
through the ease involved in doing this successfully.
Low
associated
costs
For the sake of economic feasibility, an implementing NGO would like to
pay minimal costs for a project. Costs may include:
- Procurement (purchase & transport)
- Organisational set up of costs
- Implementation costs
(Various methods require different extents of information transfer
depending on the complexity of the treatment process and whether
or not people already know of it)
- Any ongoing costs
5
Low
environmental
impact
Generally, NGOs in Kenya aim to minimise environmental impacts as
degrading the environment often has negative ramifications towards the
people they are trying to help. This is particularly applicable in Kibera due
to its density. To assess this factor, we will attempt to assess each system in
terms of production, use and disposal and associated carbon dioxide
equivalent emissions.
3
Several requirement aspects were deemed irrelevant for a comparison as they would have
been roughly constant for all treatment methods explored. Examples include the cost of
ongoing monitoring and the ease of user acquisition.
5.3 APPROPRIATE METHODS OF PURIFICATION
There are several primary methods of household water treatment being used in Kenya
(Baffrey, 2005; Alekal, 2005; Otieno, 2010):
- Boiling
- Solar water disinfection (SODIS)
- Chlorination
- Ceramic filtration
- Biosand filtration
- Flocculation
Chlorine solution, SODIS and boiling are all forms of water disinfection, that is – the
inactivation of bacteria in the water. Filtration methods disinfect water and also reduce its
turbidity. Flocculation is a water treatment method used in Kenya mainly to reduce turbidity
(Baffrey, 2005) and involves adding elements to raw water which cause the sediments to
34. 25
form larger conglomerates which can then be easily separated through sedimentation - that is,
allowing the sediments to settle at the bottom of a container over time (SDWF, n.d.). Where
water is high in bacteria and turbidity, it is recommended that disinfection methods are
coupled with sediment removal methods (WHO, 2010) but as Kibera raw water is of low
turbidity (<3NTU – Otieno, 2010), this option was not explored. The primary objective of
water treatment in Kibera is to reduce bacterial content.
In addition to flocculation/sedimentation, boiling was also excluded as a feasible option for
an NGO facilitated water treatment venture for several reasons (for detailed analysis of
boiling treatment see APPENDIX C). Perhaps the most definitive being it’s exorbitant cost if
used as a household’s only method of treatment. Combustible fuel options were explored and
the cheapest legal option was deduced to be kerosene. Despite its relatively low cost, it was
calculated that to purify an average household’s drinking water for a year with kerosene
would cost 3157.25Ksh (see APPENDIX C for derivation) – far beyond the budget of most
Kibera residents given their low incomes.
Thus, for the reasons outlined above, flocculation and boiling were excluded from further
consideration, leaving SODIS, chlorination, ceramic filtration and biosand filtration as the
most appropriate options for an NGO water treatment project. The following sections provide
specific information on each of these methods regarding how well they meet our set of user
and NGO requirements.
5.3.1 SODIS Disinfection
In some areas with a low literacy rates, uptake of SODIS has been found to be slow due to the
revolutionary yet simple nature of the principle – many people simply do not believe that the
sun can disinfect water (Treaster, 2009; Baffrey, 2005). However KWAHO observed that
89% of households exposed to their SODIS implementation were using it regularly within the
first year (Baffrey, 2005). Follow up studies 4 years after implementation started in Kibera
have shown that in areas where SODIS and relevant hygiene practice have been introduced to
users, approximately 23% of households still allow their children to consume raw water
(Graf. et al 2008). This 77% uptake of the method suggests a relatively high level of user
faith in the system. It is reasonable to attribute this to the stringent implementation strategy
used by KWAHO outlined in Chapter 4. One outcome of KWAHO’s implementation was
that many children began practicing SODIS (Otieno, 2010), illustrating that the method was
easily adopted by children.
As presented in 4.4.2, SODIS was observed to be 96.91% effective and attributable to a 42%
reduction of diarrhoeal cases amongst regular users. This indicates a strong efficacy of the
method in Kibera and that the method was easy enough for users to practice effectively. A
relative advantage of SODIS is that it is the only method from which water can be consumed
directly from the purification system, reducing risks incurred by using cups or other drinking
containers which may host bacteria.
35. 26
An average household using SODIS will use 4-6 x 1.5L bottles in use per day (Otieno, 2010),
equating to an average of 7.5L of safe drinking water provided to an average household. As
discussed in Chapter 2, the lifecycle of a bottle depends on its scratching and average project
results show that this is usually around 3 or 4 months (Otieno, 2010). We will assume that an
average household will thus use 5 bottles and to be conservative we will assume they are
replaced four times throughout the year (every 3 months), totalling 20 bottles per year. As
they are sold in Kibera for 10Ksh each (Otieno, 2010), this comes to an annual cost to the
user of 200Ksh. Bottles are currently being purchased by KWAHO for 12Ksh each, meaning
that KWAHO pays 240Ksh (12Ksh x 20) to supply an average household with bottles for a
year.
EAWAG provided expert knowledge to KWAHO and also assisted in establishing
connection with donating agencies such as Swiss Rotary Clubs, the government of
Luxembourg and the Solaqua Foundation (KWAHO, 2010).
The two primary impacts a SODIS project has on the environment are in the bottle
production phase and disposal. Negligible transport costs are involved as the bottles are
supplied from Nairobi city, only 7km away and thousands can be tucked at a time. On the
back end of the process, once the bottles have been deemed unusable, they are discarded by
the user either into a rubbish bin or more commonly in Kibera, a nearby mound of waste.
KWAHO has emphasised to users the importance of recycling (Otieno, 2010) but these
efforts are somewhat thwarted by the lack of public waste facilities and as a result, the vast
majority of rubbish ends up in gutters and large mounds which when obstructive enough, are
burnt to free up space again. However, in Kibera it is commonplace for people to scavenge
through rubbish piles collecting PET bottles and selling them to recycling companies in
Nairobi for a small price (Otieno, 2010). No published data exists regarding the proportion of
bottles which are recycled so for simplicity’s sake, we will assume half. This equates to an
average household producing the pollution of 10 burnt PET bottles per year.
NOTE:
One limitation of SODIS in Kenya is that it is ineffective in the wet seasons (April-May and
November-December). As SODIS equipment only consists of bottles, they can easily be put
away and another purification method can be used during this time.
5.3.2 Chlorination Solution Disinfection
NaOCl (sodium hypochlorite) is the most widely used point of use water disinfectant in the
world and is sold under many commercial brand names (Sobsey, 2002). In Kenya,
WaterGuard, a liquid disinfectant consisting of 1% NaOCl (sodium hypochlorite), is sold in
500mL bottles and can treat approximately 2500L of water given it is of turbidity <100NTU
(Alekal, 2005).
36. 27
The method involves adding 1mL of the solution to 5L of raw water in a clean and preferably
closed container, shaking or stirring and leaving for 30 minutes to purify (Alekal, 2005). The
sodium particles are a precipitate and they deplete over time, as they disable microorganisms.
Thus, the NaOCl remains effective until sodium precipitate is absent and the recommended
window of safe consumption is 24hrs from mixing (Alekal, 2005). Little information is
available regarding efficacy of Waterguard in Kenya however a study in nearby Malawi
showed a 69% reduction in microbiological indicators (Alekal, 2005). From this, we shall
assume that Kibera household water of 97CFU/100mL can be reduced to 30.7CFU/100mL
([1-0.69] x [97CFU/100mL]).
Populations Services International (PSI) are the producers and suppliers of Waterguard in
many countries around the world including Kenya, where the product is made locally (PSI
2010). In 2004, wholesale price in Kenya was 40Ksh and retail price was 45Ksh (Alekal,
2005), indicating a profit margin of 12.5% ([45Ksh/40Ksh] = 1.125). PSI supplies directly to
NGOs for wholesale prices. Waterguard currently sells for 75Ksh per bottle in Kibera
(Nerima, 2010) and no current wholesale prices could be found so we will assume a constant
retail profit of 12.5% and assume a current wholesale price of 66Ksh ([1-.125] x 75Ksh) per
bottle. This is assuming that retail profit margins have remained consistent in Kenya for 6
years and the low profit margin compared to other countries may be explained by the
assumption that retailers in Kenya are relatively non-cooperative and try to beat competition
through lower retail prices. As average yearly consumption of water is approximately 1825L
per household, 730mL (1825L/2500L) is required for effective disinfection per year. This
means to effectively treat water for a year, an average household requires approximately 1.5
bottles. This equates to an annual user cost of 113Ksh (1.5x75Ksh) and a wholesale cost to
the NGO of 99Ksh (1.5x66Ksh).
Waterguard has a shelf life of 12-18months (Baffrey, 2005) and taking possible presale
storage time into account, we will assume one bottle will not expire if used as the primary
method of treatment as it will be consumed in 8months ([1bottle/1.5bottles]x12months).
Regarding environmental impact, Waterguard is made in Kenya (low transport energy)
through a process involving inputs of water, electricity and salt and outputting hydrogen and
the product, NaOCl, which is a stable substance at low concentrations and so will not harm
the environment in any forms of disposal (Hooper, 2005).
Waterguard is available for purchase in Kibera and is being used to some extent (Otieno,
2010; Nerima, 2010), however there is a lack of published information on this project and so
for the purpose of gaining useful information, we will use information regarding a
Waterguard project in rural Western Kenya, implemented well, through school integration, by
CARE Kenya. A follow up study on this Waterguard project showed that approximately 73%
of people exposed to it continued regular use after the first few months and reported a
reduced diarrhoeal incidence by approximately 40% (O’Reilly, et al, 2007). Another
Waterguard project in Zambia, not far from Kenya, observed a diarrhoea reduction of 43%
amongst users (WHO, 2010), indicating some consistency in results.
37. 28
This method requires some level of literacy as it involves measurements and an
understanding of ratios, making it unsuitable for many Kibera residents, particularly children.
Waterguard has had a slow uptake in Kibera due to a commonly reported unpleasant taste
(Farkas, 2010), combined with a lack of social marketing (Baffrey, 2005). Thus, an effort to
maximise uptake would incur large implementation costs due to the lack of existing
awareness. However, the process and concept of Waterguard purification is relatively simple
to understand and have faith in so we may assume a relatively low level of implementation
effort is required.
5.3.3 Ceramic Candle Filtration
Recent publications have informed of a new locally made ceramic filtration pot costing
roughly US$1 (Kenya Ceramic Project, 2009) or 78Ksh (using 2009 exchange rate - CBK,
2010). Currently, despite the claims of effectiveness, no study results could be found from
any reliable sources and so we shall maintain focus on filters with available information. A
ceramic candle filter comparison study was performed by Amber Franz in Nairobi in 2004
(Franz, 2005) where several locally available brands of ceramic candle filters were compared
filtering Nairobi river water. Most people in Kibera source their consumption water from
water kiosks and this water is much less turbid than Nairobi river water. Regardless, the study
showed the comparative performance of each filter type. Results showed that the ‘Pelikan’
ceramic candle filter performed the best as a whole, costing only 162Ksh per unit (converting
US$2 to Ksh with 2004 exchange rate – CBK, 2010) from local stores in Nairobi, and
successfully removing 99.899% of colony forming unites from the water (Franz, 2005). As
average raw water in Kibera households contains 97CFU/100mL (Graf, et al. 2008), we may
assume that a Pelikan filter would reduce water to approximately 0.1CFU/100mL ([1-
0.99899] x [97CFU/100mL]).
Ceramic candle filters improve water quality as it passes through the ceramic walls,
collecting microorganisms and the clean water inside the candle then flows through a nozzle
at its bottom and into the receptor container (Sagara, 2000). It was assumed that the Pelikan
candle filter can be retrofitted to jerry cans widely available in Kibera as shown in Figure 7.
This involves cutting the top off a jerry can and a hole in the bottom, inserting the candle
filter into this hole and securing with some sort of locally available joining material.
38. 29
Figure 7. proposed assembly of Pelikan candle filtration system (created in MS paint)
One drawback of the Pelikan filter and most others of this kind is that it has a slow flow rate
– approximately 0.2L/hr (Franz, 2005). This means it would take approximately 25hrs
(5L/[0.2L/hr]) for one filter to purify sufficient water for an average household for one day,
or that the filter must always be in use. Thus, to effectively treat 5L of water during waking
hours, an average household would have to purchase two filters and this would increase costs
to 324Ksh (2 x 162Ksh). In addition to the Pelikan filter, a jerry can and some joining
material is required to assemble the system. As no information on prices of these components
could be found, we shall assume they incur a small cost and bring the cost of the system to
350Ksh. No information could be found on wholesale prices of Pelikan filters but as they are
a mass produced commercially available product like Waterguard, we will assume the same
NGO profit margin of 12.5% (deduced previously in 5.3.2) is required to maintain NGO
operations, making the wholesale cost to the NGO 141.75Ksh/unit (0.875 x 162Ksh).
It was assumed that as the method requires the user to assemble the filter and modified jerry
cans, the NGO implementers would assist in this set up. The method of treatment is relatively
simple and can easily be performed by children as once it is set up, only involved pouring
raw water into the filtration device and waiting. Maintenance of ceramic candle filters such as
the Pelikan involves scrubbing the receptor side of the membrane (Franz, 2005). No
information could be acquired on the durability of Pelikan filters and so we will assume they
require replacement once a year for the sake of simplicity.
No information exists regarding the taste of Pelikan treated water but as the product is
commercially successful, mechanically manufactured and does not add any new elements
into the water, we shall assume that taste is not affected negatively.
Pelikan filters are made in India (Murcott, 2006) and given a lack of available information on
transport, we shall assume that they are shipped over the Indian Ocean to Kenya’s main
coastal port Mombasa and then transported by truck to Nairobi.
No information could be found regarding the uptake of the Pelikan filter or other
commercially available ceramic candle filters in Kenya. However, as it is commercially
39. 30
available product like Waterguard, we will assume that in the context of an NGO facilitated
project, the potential user faith in this method is the same as Waterguard (73% uptake) and
depends predominantly on how well it is marketed/implemented.
5.3.4 BioSand Filtration
Biosand water filtration generally involves a non-uniform U-shaped vessel containing fine
particulate matter - Figure 8. Raw water is poured into the receptor end and due to a lower
altitude at the receptor end, water passes through the particulate matter and flows freely from
the output end. The purification principle of biosand filtration is that as water passes through
the various filtration mediums, microorganisms attach to particles within this medium so that
water output is cleaner.
Figure 8. Typical BushProof concrete biosand water filter (Lea, 2008)
There are two main forms of Biosand water filtration: slow sand and rapid sand filtration.
Typical rapid sand filtration uses coarser particulate matter, have flow rates of over 4m/hr
(where ‘m’ = the drop in input water altitude) and reduce CFU by 90%, whereas typical slow
sand filters use finer particulate matter, have flow rates of 0.1m/hr and reduce CFU by 95%
(BioSandFilter.org, 2010 (1)). Thus, in Kibera where household raw water is of
97CFU/100mL, slow sand filtration is most desirable as it can treat water to roughly
4.85CFU/100mL ([1-0.95] x [97CFU/100mL)), which is competitive with other methods
explored in this section. Slow biosand filtration is already present in Kibera (Otieno, 2010)
but no published information could be found on details of this project. There are several
agencies in Kenya providing training and networking to NGOs looking to implement biosand
projects, the most established being BushProof, who advocate slow biosand filters
(BushProof, 2010 (3)). For the reasons mentioned, we will select slow biosand filtration as
the most ideal method in Kibera.
40. 31
BushProof is an international agency endorsed by World Health Organisation and aims to
assist NGOs in making their projects most effective (BushProof, 2010 (2)). BushProof offers
services including (BushProof, 2010(1)):
- Strategic planning
- Management development
- Performance management
- Networking assistance for funding and further assistance
The most commonly made slow biosand filters made in Kenya are made with a concrete
housing material formed with steel moulds, PVC piping for the outflow section, with sand
and gravel as the filtering medium (Baffrey, 2005). BushProof have experience in projects
promoting such concrete biosand filters. For large scale implementation, it is most feasible
for a Kibera NGO to manufacture its own biosand filters as sourcing them from elsewhere
would incur larger manufacture and transportation costs. Set up costs include the purchase of
a steel mould costing 35 000Ksh and material costs involved in manufacture of a single
biosand filter include: 20Ksh for concrete, approximately 100Ksh for gravel and sand,
approximately 100Ksh for a sieve, 10Ksh for the water needed to wash the sand with the
sieve (cost of 80L of water using an average price of 2.5Ksh./20L as stated in 3.2) and labour
costs (Baffrey, 2005). PVC pipes are also part of the system but no information could be
found regarding prices in Kenya so we will assume it to be low as PVC pipe is widely
available and used in lengthy connections between water kiosks and municipal water supply
lines (see 3.2). Labour and transport costs were unobtainable but are expected to be high,
particularly due to the heavy weight of 72kg for each concrete housing (CAWST, 2008).
Information about a concrete biosand project in rural Kenya informs of a production cost
totalling 800Ksh per filter where sufficient funding allowed the distributing NGO to sell at
the same price (Baffrey, 2005). For the sake of achieving a comparison later, we will assume
transport and manual labour costs are 200Ksh each per filter produced and the remaining
unaccounted costs of the 800Ksh sale price are assumed NGO cost recovery (ie, paying off
the 35 000Ksh steel mould, etc).
Slow biosand filters accumulate most of their microorganisms in the top layers of sand,
which become clogged over time, decreasing the flow rate and so recommended maintenance
involves replacing the top layer of sand with new filtered sand (large particles removed using
sieve) when the flow rate becomes insufficient (BioSandFilter.org, 2010 (2)). Thus, in
addition to purchase costs, users must also pay for top up sand. These prices were considered
negligible in our user cost figure as it is a rough estimation and does not take into account
possible NGO profit margins.
No information could be found on the durability of concrete biosand filters in use however, it
was noted in a one production operation in Kenya that 4 out of 2400 concrete filters produced
cracked during transport (Baffrey, 2005). As this figure is low, we will assume that biosand
filters are relatively robust but breakage is possible (unlike SODIS, Waterguard and boiling).
41. 32
Regarding environment, production is done with manual labour only and thus produces no
emissions. Also, the PVC piping is the only component which incurs an environmental
impact on disposal as the rest are raw earth materials. We shall assume that disposed biosand
filters can be crushed and concrete fragments recycled for some other use (rocks are often
used to hold down sections of corrugated iron on household roofs) and if the pipe remains
intact, it can also be recycled for some other use (if not, it is most likely going to end up in a
rubbish pile and burnt – similar to SODIS and Waterguard bottles). Also, the sieve used to
filter fine sand could most likely be used in another application such as cleaning rice or
beans. The main environmental impacts of biosand filters are incurred through raw material
extraction from quarries and transportation. As materials are locally sourced in Kenya – a
developing country, we will assume that such extraction is not a large scale operation and
much of the work is done through manual labour. Larger emissions are most likely incurred
through transport due to the heavy weights of the materials.
As with ceramic candle filtration, this method is relatively simple and can easily be
performed by children, involving pouring raw water into the filtration device and waiting.
Biosand filters do not negatively affect the taste of water (Lantagne, et al).
No information could be found regarding uptake on any biosand filter projects. The method is
similar to that of ceramic candle filtration (pouring raw water in and waiting for treated water
output) and so we will assume that if equal levels of information transfer and marketing are
invested by the NGO – the users will understand the two purification processes equally.
Therefore we assume that the only difference in potential user faith between methods is based
on visual appearance of the system and its involvement of sand/gravel. The Pelikan filter is
machine manufactured and well presented whereas the boisand manufacture process is less
refined and the end product most likely looks less technologically advanced. Also, the use of
sand and gravel may decrease faith in users as they may associate these materials with dirty
surrounding areas of Kibera. Due to these reasons and assumptions, we will assume further
that the potential faith in biosand filtration is marginally less than the Pelikan ceramic candle
filter and for the sake of simplicity, we will assume a 60% uptake rate.
5.4 WATER TREATMENT METHODS VS REQUIREMENTS
This section uses the information divulged in the previous section to quantitatively compare
each method’s performance regarding the user and NGO requirements. Scoring schemes were
used subjectively and all scores were rounded to one decimal place.
5.4.1 Efficacy
Table 3 compares the efficacies of methods examined:
