This document provides definitions of key environmental health terms and discusses various topics related to water supply and health. It defines environment, discusses definitions of health from WHO and environmental health sciences. It describes the different contributors to the environment that can impact health. It also discusses the various components of environmental health including water supply, sanitation, hygiene and others. The document elaborates on different water sources and their quality, importance of water, water requirements and impurities in water. It discusses waterborne, water-washed, water-based and water-related diseases and their means of transmission and prevention.

1. Environmental health course lecture note
Melaku Nigussie
(BSc, MPH)
Email: melakun66@gmail.com

2. Environment
• Definitions: The circumstances, objects, or
conditions by which one is surrounded
or
• „
The complex of climatic, edaphic (soil-based),
and biotic factors that act upon an organism or
an ecologic community

3. “The Environment’’
Public Health Definition
• All that which is external to the individual host. [It]
can be divided into ፡
• physical, biological, social, and cultural factors,any or
all of which can influence health status in
populations.−Last, J. M. (Ed.). (1995). A Dictionary
of Epidemiology(3rd – edition)

4. Definitions: Health
• „
A state of complete physical, mental, and social well-
being and not merely the absence of disease or
infirmity- WHO. (1948)

5. What Is Environmental Health Sciences?
• “The study of those factors in the environment that affect
human health”
• −Factors (“pollutants”or “toxicants”) in air, water, soil, or
food
• −Transferred to humans by inhalation, ingestion, or
• absorption
• −Production of adverse health effects

6. Contributors to the “Environment”
• „Chemical−Air pollutants, toxic wastes, pesticides, etc
• „
Biologic−Disease organisms present in food and
water−Insect and animal allergens
• „
Physical−Noise, ionizing and non-ionizing radiation
• „
Socioeconomic−Access to safe and sufficient health care

7. Components of environmental
health
Description Concerns
Personal hygiene Hygiene of body and clothing
Water supply Adequacy, safety (chemical, bacteriological, physical) of water for
domestic, drinking and recreational use
Human waste
disposal
Proper excreta disposal and liquid waste management
Solid waste
management
Proper application of storage, collection, disposal of waste. Waste
production and recycling

8. Vector control Control of mammals (such as rats) and arthropods (insects such as
flies and other creatures such as
mites) that transmit disease
Food hygiene Food safety and wholesomeness in its production,storage,
preparation, distribution and sale, until consumption
Healthful housing Physiological needs, protection against disease and accidents,
psychological and social comforts in residential and recreational
areas
Institutional hygiene Communal hygiene in schools, prisons, health facilities, refugee
camps, detention homes and settlement areas
Water pollution Sources, characteristics, impact and mitigation
Occupational hygiene Hygiene and safety in the workplace

9. I. Water supply
• Water is essential for life. Man can live nearly two
months without food, but can live only three or four
days without water. In general 70% of human body
weight is water and a human being needs two liters of
water per day as minimum.

10. • Water is located in all regions of the earth. The problem is
that the distribution, quality, quantity and mode of
occurrence are highly variable from one locality to another.
• Water is the most widely occurring substance in the world.
• Over 72% of the earth's surface is covered by water. This
means that if the body of water were evenly distributed, it
would cover the globe to an average depth of over 4
kilometers.

11. • Out of the 72% of the earth’s surface water, 97.2% is in
the ocean, which is unfit for human consumption, as it is
too salty to be used for drinking and irrigation without
desalination. Desalination is too expensive to consider as
a water purification method.
• Another 2% of the remaining water lies frozen in glaciers
and in icecaps, and is mostly unreachable.
• The tiny usable portion is about 0.8% of the total, which
is neither evenly distributed nor properly used.

12. • Palatable water: water that is safe for drink, pleasant to the test and
usable for domestic purpose, but it may have contamination
• Safe water: water intended for drinking and domestic use whose
limits for toxic substances, bacteriological and organo leptic level
conform to the requirment of the standard
• Potable: free from any destructive substances, likechemicals,
microorganisms and contaminants

13. Properties of Water
• Pure water consists of two atoms of hydrogen and
one atom of oxygen chemically combined.
• The chemical symbol is H2O and the chemical name
is hydrogen monoxide.
• Water exists in three states: as a liquid, as a solid (ice
and snow), and as a gas (water vapor).
• It is a very stable chemical substance.
• Water has a maximum density of one at a temperature
of 4OC. It boils at 100OC and freezes at 00C

14. • Pure water is practically colorless, odorless and
tasteless. Any deviation from these physical
characteristics should be considered as an indication
of impurity.
• Water has the ability to dissolve solids and to absorb
gases and other liquids. Hence, it is often referred to
as the “universal solvent”.
• Because of this solvent power, all natural water
contains minerals and other substances in solution,
which have been picked up from the air, the soil, and
rocks

15. • Water has very high molecular attraction both for its
own molecules (cohesion) and for molecules of other
substance (adhesion).
• Because of this particular characteristic, a large
quantity of water is held in rock particles and by plant
roots in the soil.
• The PH of pure water is 7 (neutral).

16. SOURCES OF WATER
• Different sources of drinking water broadly categorized
as: ground and surface water sources.
• The quality of water could vary by source type.
• Groundwater may comprise excess chemicals, but is
usually free from harmful bacteria and viruses unless
the water is polluted for example by nearby pit latrines
or during abstraction and transport

17. • surface water is contaminated with harmful bacteria
and viruses and may also contain other contaminants
such as herbicides, pesticides and excess chemicals.
• Rainwater is usually clean but may pick up impurities
from air and the surface from which it is collected.

18. The water sources are classified into three
1. Improved water sources: includes piped water into
dwelling, yard or plot, public tap or standpipe, tube well
or borehole, protected dug well, protected spring, and
rainwater collection.
2. Unimproved water sources: includes unprotected dug
well, unprotected spring, cart with small tank or drum
provided by water vendor, tanker truck provision of
water, and bottled water
3. Surface water sources: (river, dam, lake, pond, stream,
canal, irrigation channel)

19. Importance of Water
 It is impossible to have a clean and sanitary
environment without water.
 Water is necessary in promoting personal hygiene and
in cleaning the environment
 Without an adequate and wholesome water supply,
health cannot be maintained.

20. Most of the foods that man eats contain water.
For example:
- Milk contains about 88% water.
- Egg contains about 66% water.
- Fish are 80% water.
- Potatoes are 75% water.
- Beef is 77% water

21. • It is essential to run industries.
• Nearly all modern industries are thirsty; they need water.
For example:
• - It takes about 10 liters of water to produce one litter of petrol.
• It takes about 600 liters of water to produce 1kg of woolen
cloth.
• - It takes about 3500 liters of water to produce 1kg of dry
cement.

22. • It is important for agriculture, animal breeding and
fishing.
• Water is a valuable source of energy(capable of
generating hydroelectric power).
• Water facilitates transportation and navigation. For
example, the Baro River is one of the rivers used for boat
transportation in Ethiopia.
• Water plays an important role in recreation activities.
Lake Langano is an attractive lake for recreation.

23. Water Requirements
• The availability of an adequate and safe supply of water is one
of the major requirements for the control of a large number of
diseases.
Quantity of water
• Water is used for domestic, industrial, agricultural, public use
and firefighting.

24. The total consumption largely depends on:
• ƒ
The climatic condition
• ƒ
Cost of water
• ƒ
Hygienic practice standards
• ƒ
Type of supply (continuous or intermittent)
• ƒ
Custom and habits of inhabitants
• ƒ
Pressure in pipe lines
• ƒ
Accessibility of water source

25. ƒ
• Population
• ƒ
Amount of water available
• ƒ
Financial position of population
• ƒ
Efficiency of management system
• ƒ
Type of industrial activities
• ƒ
Fire extinguishing service, etc.

26. Estimation of demand of water
• Requirement is generally expressed in terms of
average number of liters of water per capita per day
throughout the year.

27. Purpose Consumption l/d/c
• Drinking--------------------------------- 2.3
• Cooking -----------------------------------4.5
• Ablution --------------------------------- 18.2
• Washing of utensils and houses -------13.6
• Flushing of w.c ------------------------ 13.6
• Bathing -------------------------------- 27.3
• Total ----------------------------------- 106.8

28. Impurities of Water
• Water is not absolutely pure in nature.
• Impurities vary from dissolved gases, chemicals, minerals, to
suspended matter and disease-causing micro-organisms. Some
can be seen with the naked eye, while others that cannot be seen
are detected by taste or smell or other laboratory methods.
• As it flows over the earth’s surface, it may pick up dirt, micro-
organisms, chemicals and anything else in its path which can be
moved or dissolved.

29. Impurities of water
A. Suspended Impurities
1. Micro-organisms:
• they may get into water from the air with dust, etc., as
rain falls, or
• when soil polluted with human and animal wastes is
washed into the water source.
• The latter type of impurity in water is the most
dangerous one because microorganisms are
pathogenic and cause disease

30. 2. Suspended solids
• Minute particles of soil, clay, silt, soot particles,
dead leaves and other insoluble material get into
water because of erosion from higher ground,
drainage from swamps, ponds, top soil,

31. • Toxic chemicals such as insecticides and
pesticides are also included in this
category, introduced to streams either as
industrial wastes or drained in after rain
from land treated with these chemicals.
Generally, suspended solids cause taste,
color or turbidity.

32. 3. Algae
• Algae are minute plants that grow in still or stagnant
water. Some algae are green, brown or red, and their
presence in water causes taste, color and turbidity.
• Some species of algae could be poisonous both for
aquatic animals and humans

33. B. Dissolved Impurities
1. Gases
• Oxygen (02), carbon dioxide (C02), hydrogen sulphide (H2S), etc, find their way into water
as it falls as rain or,
• in the case of the latter two, from the soil as water percolates through the ground. All
natural water contains dissolved oxygen, and in certain circumstances carbon dioxide.
• The presence of C02and H2S (but not 02) causes acidity in water. In addition, H2S imparts a
bad odor to the water.

34. 2. Minerals
• Minerals get into water as it percolates downward though the earth
layers. The type of minerals dissolved will depend on the nature of
the specific rock formation of an area.
• Most common dissolved minerals in water are salts of calcium,
magnesium, sodium, potassium, etc. Salts of the first two elements
cause hardness in water, while salts of the latter two elements cause
alkalinity.
• Salts of toxic elements, such as lead, arsenic, chromium, etc, get into
water mainly as industrial wastes dumped into streams.

35. WATER SUPPLYAND HUMAN HEALTH
• According to WHO survey 80% of all illnesses in
developing countries are water-associated.
• The use of unsafe water causes high prevalence of
diarrheal diseases among children resulting in high
infant and child mortality rates.
• Water and sanitation have emerged as a primary health
care Component so that it will be able to alleviate the
associated morbidity and mortality.

36. Water supply is generally linked with or affected by factors such
as:
• Economy, Population growth, Educational status,
Customs, traditions, Governmental concern, etc.
Hence, the provision of safe and adequate water supply programs
requires integrated efforts of different concerned sectors
including the community to be benefited for its effective
achievements.

37. • According to the health indicators of MOH, The safe
water coverage in 1992 E.C. for urban areas was
83.5% and 24.7% in the rural parts of the country
where the majority of the population is living.

38. Water, Health and Disease
• The normal functioning of the human body depends
entirely upon an adequate quantity and quality of
water.
• if the water is from contaminated sources, it causes
numerous water-associated diseases

39. • In the developed world, water-associated disease are
rare, due to : the presence of efficient water supply
and waste water disposal systems.
o However, in the developing world, the majority of
people are without a safe water supply and adequate
sanitation

40. A WHO survey has highlighted the following facts:
• Each day, 30,000 people die from water-associated diseases.
• In developing countries, 80% of all illnesses are water associated.
• Safe, adequate and accessible supplies of water, combined with
proper sanitation, are basic needs.
• Safe, adequate and accessible water supply can help to reduce many
of the disease affecting under-privileged populations especially
those who live in rural and urban fringe area. . .

41. • All water-associated disease requires an
infectious agent, a transmission route and the
exposure of susceptible living organisms for
their spread

42. Water-associated Disease
Water-associated disease: can be defined as a disease
in relation to water supply and sanitation. There are
four categories:
1. Waterborne disease
2. Water-washed disease
3. Water-based disease
4. Water-related disease

43. 1. Waterborne diseases:
• Several infections enteric or intestinal diseases of
man are transmitted through water contamination by
fecal matter.
• Pathogens excreted in water by an infected person
include all major categories such as bacteria, viruses,
protozoa and parasitic warms.(typhoid, cholera, gastro-
enteritis etc)

44. Fig 1. The classic waterborne disease infection cycle

45. Prevention
• proper liquid waste management system/avoid open
defication
• Safe water storage,
• Water treatment (Agar,Cl, home sand filter is very
essential.
• Health education

46. Fig: Household water treatment processes

47. 2. Water-washed diseases
 These comprise diseases linked to a lack of water for personal
hygiene. Examples are:
o Dermatological disease such as scabies
o Ophthalmic disease such as trachoma and conjunctivitis
o Louse-borne diseases such as louse borne typhus and
relapsing fever. Lack of good personal hygiene and un ability
to wash clothes encourages the proliferation of lice and the
problems associated with their presence (itching, scratching,
skin sores).

48. Prevention
• Avail adequate water supply
• Accessing water supply
• Health education

49. 3. Water-based diseases
• These are diseases caused by infectious agents that are
spread by contact with water.
• The essential part of the life cycle of the infecting agent
takes place from an aquatic animal.
• A number of diseases depend upon the pathogenic
organisms spending part of their life cycle in water or in
an intermediate host which lives in water.

50. • Many of the diseases in this class are caused by
worms, which infest the sufferer and produce eggs,
which are then discharged in feces or urine.
• Typical examples are schistosomiasis and
dracunculiasis (guinea worm).

51. prevention
• Avoidance of contact with and ingestion of
contaminated water.
• Increase access to safe water not only for drinking, but
also for non-drinking purposes,
o such as clothes washing, bathing, and swimming, to
decrease contact with contaminated surface water
• Promote behavior change to discourage the use of
contaminated surface water for activities

52. • Reduction of intermediate hosts (snail) by using
“endod” or Lemma toxin.
• Reduce open defecation and urination community-
wide to minimize water contamination

53. 4. Water-related diseases :
• These are diseases transmitted by insects that live close to water.
• Infections are spread by mosquitoes, flies and other insects that breed in
water or near it.
• There are a number of diseases which are spread by insects that breed
or feed near water so that their incidence can be related to the proximity
of suitable water sources.
• Infection with these diseases is in no way connected with human
consumption or contact with the water. ( Malaria, sleeping sickness,
yellow fever, onchocerciasis, etc. )

54. prevention
• Provide hygiene education
• Increase access to clean water to encourage water use
for good hygiene.
• Cover and/or treat water storage systems to limit
mosquito habitat
• Environmental management
• Use insecticide chemicals
• Treatment

55. Drinking water quality parameters
• Water quality parameters are classified in to three
aspects such as physical, chemical, and biological
characteristics of water in association to the set of
standards.
1. Physical aspects of drinking water quality: residual
chlorine, temperature, color, odor, taste, turbidity,
PH, electrical conductivity, and total dissolved solids

56. • Chlorine leaves a disinfectant residual that assists
in preventing recontamination through out distribution,
transport, and household storage of water.
• The absence of a chlorine residual in the
distribution system may in certain circumstances,
indicate the possibility of post-treatment
contamination

57. • The pH of pure water refers to states of acidity
and alkalinity of solutions with respect to
hydrogen and hydroxide ions can be expressed by a
series of positive numbers between 0 to 14.
• In general, water with a pH of 7 is considered neutral
while lower than this referred acidic and a pH
greater than 7 known as basic.

58. • Normally, water pH ranges from 6 to 8.5.
• It is noticed that water with low pH tends to be
toxic and with high degree of pH, it is turned into
bitter taste. According to the WHO standards, pH
of water should be 6.5 to 8.5

59. • Turbidity is a measure of the degree of cloudiness or
muddiness of water.
• It is caused by suspended matter such as clay, silts,
finely divided organic and inorganic matter, soluble
colored organic compounds, plankton, and other
microscopic organisms.

60. 2. Chemical aspects of drinking water quality
parameters: The major chemical or inorganic
parameters of drinking water quality mainly classified
as; hardness, calcium, magnesium, chloride, sulphate,
fluoride, alkalinity, nitrate, phosphate and ome toxic
metals such as; copper, chromium (cr+6), Iron,
Manganese, etc.

61. Hardness
• Hardness of drinking water is due firstly to
calcium and magnesium carbonates and
bicarbonates (which can be removed by boiling)
and calcium and magnesium sulfate and chloride

62. 3. Bacteriological aspects of drinking water quality
• The type and numbers of microorganisms present in
the water determine the microbiological properties of
water

63. • Maximum permissible level is a requirement whose non fulfillment would
disqualify water for drinking and domestic use because of its probable
hazard to health.
• Table 1: Physical Characteristics of Drinking Water
Characteristics Maximum permissible level
Odor Unobjectionable
Taste Unobjectionable
Turbidity ,NTU
5
color
15

64. • Table 2: Chemical requirements(Characteristics that Affect the Palatability
of Drinking Water)
Substance or characteristic Maximum permissible level
Total hardness (CaCO3)
Total dissolved solids mg/Ll 1,000
Total Iron (Fe) mg/L
Manganese (Mn) mg/L
Ammonia (NH3+NH4+) mg/L
Residual free chlorine mg/L
Magnesium (Mg) mg/L
Calcium (Ca) mg/L
Copper (Cu) mg/L
Zinc (Zn) mg/L
Sulfate (SO4) mg/L
Chloride (Cl) mg/L
Total alkalinity (CaCO3) mg/L 200
Sodium (Na) mg/L
300
1,000
0.3
0.5
1.5
0.5
50
75
2
5
250
250
200
200

65. Table 3: —Bacteriological levels
Organism Maximum permissible level
Fecal streptococci 100 ML Must not be detectable
Coliformorganisms, number per 100
mL
Must not be detectable
E. coli, number per 100 mL Must not be detectable
Total viable organisms, colonies per
mL
Must not be detectable

66. Review Questions
1. Why are water-associated diseases more common in
developing countries than developed countries?
2. Write the two main types of water pollution.
3. How are waterborne diseases transmitted? Give some
examples.
4. Write the differences between water-washed and water
based diseases.
5. Write the prevention methods of water-related diseases

68. Community waste disposal
• Domestic Waste: is waste, which is either solid or liquid
generated in residential areas, Commercial settings and
institutions.
• Waste in general terms is defined as an unwanted as it is
obviously undesirable.
• It is nevertheless an inevitable and inherent product of social,
economic and cultural life.

69. • The indiscriminate disposal of waste, both liquid and solid,
adversely affects the immediate human environment by
degrading the natural phenomena hence, exerting health
risk to exposed population.
• Health risks may be carried through different vehicles
including flies, dogs, rodent and others that scavenge on the
waste.

70. wastes are classified as solid and liquid
• Solid Waste Management: A systematic
administration of activities that provide for the
collection, source separation, storage, transportation,
transfer, processing, treatment and disposal of solid
waste

71. Public Health importance of solid waste
• It can be best media for the growth of microorganisms
• Attraction of arthropods such as common housefly,
mosquito, etc
• Attraction of rodents and other animals e.g. rats mice
dogs cats
• Open dump can contaminate water sources
• Can contaminate food supply and cause food borne
disease

72. • Hospital and pathological wastes are potential disease
carrying waste products
• Radioactive wastes are highly dangerous
• It can create fire accident
• Slum areas
• It can create nuisance: Bad odor, smoke, dust ,Aesthetical
problem ,Discomfort: sneezing, coughing

73. Classifications of solid waste
• Solid waste can be classified into two categories by its
characteristics. These are:
• Organic solid waste
• Inorganic Solid waste
• Organic solid waste: Wastes that are generally biodegradable
and decompose in the process of which emits offensive and
irritating smell when left unattended.
• ⇒Putrescible wastes e.g. Garbage

74. • Inorganic solid waste: Solid matter that does not
decompose at any rate This category of waste matter
may be combustible depending on the type of the
nature of the material they constitute.
• ⇒Non-putrescible wastes e.g. Rubbish

75. Functional Elements of solid waste management
system
• There are six functional elements in the activities associated
with the management of solid wastes from the point of
generation to final disposal site. These are:
• 1. Waste generation
• 2. On-site handling (sorting, storage and processing)
• 3. Collection
• 4. Transfer and transport
• 5. Processing and recovery
• 6. Disposal

76. Description of the six main functional elements of solid
waste management system
• Waste generation: those activities in which materials are
identified as no longer being of value and are either thrown
away or gathered together for disposal.
• On-site handling, storage, and processing: activities
associated with the handling, storage, and processing of solid
wastes at or near the point of generation.
• Collection: those activities association with the gathering of
solid wastes and the hauling of wastes to the location where
the collection vehicle is emptied.

77. • Transfer and transport: Those activities association with
(1) the transfer of wastes from the smaller collection vehicle to
the larger transport equipment and
(2) the subsequent transport of the wastes, usually over long
distance, to the disposal site.
• Processing and recovery: Those techniques equipment and
facilities used both to improve the efficiency of the other
functional elements and to recover useable materials,
conversion products, or energy from solid wastes.

78. • Disposal: Those activities associated with ultimate disposal of
solid wastes Interrelationship of functional elements
comprising a solid waste management system
Main sources of solid waste generation
• Residential (domestic or house hold) ,Commercial ,Institutional
, Construction Demolition ,Treatment plant sites ,Industrial
and Agricultural

79. Waste handling and separation, storage and processing at the
source
⇒The best place to separate waste materials for reuse and recycling is
at the source of generation
⇒Home owners should be aware of separation of News paper, and
cardboard, bottles, yard wastes, aluminum cans, ferrous materials
and especially hazardous wastes
⇒Waste processing is used to reduce the volume, recover usable
materials, and alter the physical form of the solid wastes

80. Solid waste collection
• Collection is provided under various management
pattern/arrangements:
• Municipal/Rural Communities Organization- using simple and
locally available technology such as Donkey Drawn Cart,
• Private services such as contractors
•Scavenger system: Individuals may collect and use wastes like
paper, metal, containers, clothes etc for reuse or recycling.

81. Common solid waste disposal methods
• Composting: Composting is not final disposal method but
converting waste into a useful product. Compost has been used in
both the rural and semi urban areas of Ethiopia for quite a long time
as a soil conditioner to grow mostly vegetables and crops but
without processing it.
• Controlled Tipping/Burying: It is a way of isolating any type of
waste without bothering to sort or separate. Controlled tipping is a
simple, effective and relatively cheaper method of refuse disposal.
This method involves preparation of hole in the ground with a depth
of 1-2 meters and width and length of 60 centimeters for a
household.

82. • Ploughing in fields: Applying waste in farm fields for soil
conditioning has been practiced in Ethiopia for a long time. This is a
practice with a dual purpose; it is one hand a way of waste disposal
and on the other hand a means of recovering and reusing waste for
soil conditioning
• Incineration: is a high temperature dry oxidation process that
reduces organic and combustible waste to inorganic, incombustible
matter and resulting in a very significant reduction of waste volume
and weight

83. Other disposal methods
• Sanitary landfill: A method of disposing a refuse on land
without creating nuisances or hazards to public health or
safety.
• Open dump: The most unsanitary disposal option

84. Liquid Waste Management
• A systematic administration of activities that provide for the
proper handling, treatment and disposal of liquid
waste/wastewater or sewage
.

85. Public health importance of waste water/sewage
• contamination of surface water, ground water, and the soil Solid
and Liquid Waste Management thereby posing health problems.
• These phenomena persist in developing countries and affect
almost every one.
• In Ethiopia, to day, all wastes even in large international cities
like Addis Ababa are drained to the side of roads to ultimately
join small streams or rivers to flow down stream causing water
pollution

86. Classifications of liquid waste/sewage
• Waste water or sewage that are generated from a home or
community including toilet, bath, laundry, lavatory, and kitchen-
sink wastes, and surface run off may be classified into four.
These are:
• Sanitary sewage : domestic sewage contains human wastes and
wash water from homes, public buildings or commercial and
industrial establishments
• Industrial sewage : the used water from manufacturing
processes, usually carrying a variety of chemical compounds.

87. • Storm sewage :the surface run off caused by rainfall, it carries
organics, suspended and dissolved solids, and other substances
picked up as it travels over the ground
• Mixed sewage (a mixture of all) :

88. Liquid waste/sewage disposal methods
A. Disposal by dilution/ “Self-purification of water bodies”
• It is a common practice in some communities to discharge raw
sewage into near by water bodies such as rivers, streams, etc., so
that it is diluted or reduced in strength by the water.
⇒Unsanitary:
• Nuisance (creating offensive condition)
• Water and soil pollutions (a aquatic life start to die off)
• Spread of infectious organisms greatly increases

89. B. Cesspool
• A cesspool is a pit dug in the ground in order to receive waste
water/sewages from kitchen, toilet or barns. Cesspool can be
classified in to two kinds by its removal mechanisms. These are:
1. The leaching type of cesspool :allow the liquid to seep, leach or
percolate into the ground.
2. The watertight cesspool :Inside water tight tank sewage
undergoes anaerobic
decomposition but should not considered sewage treatment
ƒ
Problem: periodic emptying and disposal of contents

90. Contaminated Waste Management
• Wastes from hospitals and healthcare facilities may be
contaminated (potentially infectious) or non-
contaminated.
• Approximately 85% of the general waste produced by
health institutions is non-contaminated waste and
poses no infectious risk to persons who handle it

91. • Contaminated wastes include blood, pus, urine, stool
and other body fluids, as well as items that come in
contact with them, such as used dressings.
• Wastes from operating rooms (human tissue, blood or
blood soaked sponges, gauze or cotton) and laboratories
(blood, feces, sputum, urine specimens and
microbiological cultures) should be considered
contaminated.

92. Purpose of contaminated waste management
The purpose of contaminated waste management is to:
• Protect people who handle waste items from accidental
injury,
• Prevent the spread of infection to healthcare workers who
handle the waste,
• Prevent the spread of infection to the local community,

93. • Safely dispose of hazardous materials (toxic
chemicals and radioactive compounds).

94. How to dispose of liquid contaminated
wastes
• STEP 1:Wear PPE (utility gloves, protective eyewear
and plastic apron) when handling and transporting
liquid contaminated wastes.
• STEP 2:Carefully pour wastes down in a utility sink
drain or into a flushable toilet and rinse the toilet or
sink carefully and thoroughly with water to remove
residual wastes. Avoid splashing.

95. STEP 4:Decontaminate specimen containers by placing
them in a 0.5% chlorine solution for 10 minutes
before washing them.
STEP 5:Remove utility gloves (wash daily or when
visibly soiled and dry).
STEP 6:Wash and dry hands

96. How to dispose of contaminated sharps
• Disposable sharp items (hypodermic needles, suture needles,
razors and scalpel blades) require special handling because
they are the items most likely to injure the community
healthcare workers who handle them as well as people in the
community if these items go to the landfill.
• STEP 1:Wear heavy-duty utility gloves.

97. STEP 2:When the sharps container is three-quarters full it should be
capped, plugged or taped tightly closed.
• Be sure that no sharp items are sticking out of the container.
STEP3:Dispose of the sharps container by burning, encapsulating or
burying.
STEP 4:Remove utility gloves (wash daily or when visibly soiled,
and dry).
STEP 5:Wash hands and dry them with a clean cloth or towel or air
dry.

98. Human Waste Management
• Sanitation is defined as the “safe management of human
excreta and other waste product produced by the dayto day
activities of people”.
• This definition includes the hardware and software
components, as effective interventions need to stimulate both
the constructions of sanitary facilitiesfor waste management
and their hygienic use

99. • Fecal-oral diseases are among the most obvious endemic
diseases throughout the developing countries and more so in
Ethiopia.
• The effectiveness of sanitation as an intervention to the
fecal-oral diseases varies because of the following reasons.
1. Bacterial infection such as cholera involve large infective
doses, hence they are more susceptible to control through
sanitation.
2. Polio or hepatitis require only a small dose to cause the
disease

100. • 3. Many diseases such as salomellosis involve transmission
cycles that can pass through animal hosts, which limits the
benefits of controlling only human excreta if the disease can
be transmitted through the feces of chickens in the household

101. The Facts in Ethiopia Indicates:
• ƒ
About 80% of diseases are related to poor sanitation and
unsafe water supply
• Diarrhea and parasitic infections are classified in the top 10
diseases causing high morbidity and mortality especially among
the under five children

102. Ways fecal borne diseases are transmitted
• As could be seen in the following life cycles man is the
reservoir of most of the intestinal parasites, bacteria and
viruses.
• In the transmission of these diseases from the infected person
or carriers of disease to the healthy person the chain of events
usually involved the following:
• 1. A causative or etiologic agent;
• 2. A reservoir or source of infection of the causative agents
• 3. A mode of escape from the reservoir;

103. 4. mode of transmission from the reservoir to the potential new
host;
5. A mode of entry into the new host;
6. A susceptible host