Collection of water samples

1. WATER QUALITY

2. Characteristics of safe Water
No smell
Clear
Free form SS
Have minerals and salts needed by the body but in safe concentrations
Free from harmful microorganisms

3. Sources of water
Ground water
Surface water
Rain water
Note:
Depending on the source, water may pick many things which can affect its quality

4. Multi-barrier Approach to Safe Drinking
Water
The best way to reduce the risk of drinking unsafe water is to use the multi-barrier approach.
The five steps of the multi-barrier approach to safe drinking water are:
1. Protect your source water
2. Sediment your water
3. Filter your water
4. Disinfect your water
5. Store your water safely

5. Water Quality Parameters
1. Physical (temperature, smell, taste, colour, turbidity)
2. Chemical (pH, minerals, metals, salts)
3. Microbiological (bacteria, virus, protozoa, helminth-worms)
Note
Priority is based on the parameter that will have impact on public health
Microbiological quality is the main concern

6. Planning for Water Quality Testing
1. Review the need - Why do you need to do water quality testing?
2. Develop your objectives - What are your objectives for testing the water quality?
3. Identify the test parameters - What water quality parameters are you going to test for?

7. Sanitary Inspection
A sanitary inspection is an on-site inspection of a water supply to identify actual and potential
sources of contamination.
1 Reveals conditions or practices that may cause contamination incidences
2. Reveals possible sources of contamination
3. Identifies risks that may microbial and physical quality of water.

8. SAMPLE COLLECTION AND HANDLING

9. Why do we need to collect a water sample?
Most water quality analyses cannot be done on site (in situ). Therefore, a
representative volume of water at a specific point of interest has to be collected
for analysis in a laboratory.

10. Why is it important to know how to collect
water samples?
Wrong sampling procedures and methods will affect the accuracy and reliability
of analytical results and lead to misleading conclusions on the quality of the
water supply.

11. What is a representative water sample?
A representative water sample can be described as a sample that
meets the objectives of sampling, and that has been collected at a
place that truly represents the water at the point of concern in the
water supply system

12. Where must water samples be collected?
Note: The actual sampling point in the system is determined by the objective of
the sampling program
 The source (if the objective is to determine whether a water source is suitable
for domestic purposes, or what level of treatment is required)
 The outflow from the water treatment works (if the objective is to determine
operational control and product quality)
 A distribution system (if the objective is to determine whether any changes in
water quality occur in the distribution system)
 A point of use (to determine if the water is fit for use).

13. Parameters to be tested
 If the water source is near an industrial area, then, depending on the type of industry, organic
compounds and/or metals must be included on the list of variables to be determined.
 If the water source is in an agricultural area then the possible presence of herbicides,
pesticides and fertilisers must also be determined.

14. Sampling Techniques
Surface Water

15. Sampling Tech…cont
Treatment and distribution system and point of collection

16. SAMPLING PROCEDURE
Sampling Instructions
BIOLOGICAL PARAMETERS  Remove any attachments on the faucet
 Allow water to flow for 5 or 6 minutes before sampling
 Do not rinse or overfill container
 Do not touch the inside of the sample bottle or its cap
CHEMICAL AND PHYSICAL PARAMETERS  Rinse the bottle and cap three times with sample water
 Fill the bottle to within one to two inches from the top.
 Refrigerate the samples to temp < 40C
METALS  Wear gloves and eye protection when handling acid and while collecting
samples.
 If the bottle contains a preservative, do not rinse the bottle. If the
preservatives are not included in the bottle, rinse the bottle and cap three
times with sample water
 fill the bottle, and then carefully add the preservatives following the
instructions provided by the laboratory.
 The bottle should be filled to within one to two inches from the top.

17. Physical Parameters
Determinatio
n
Container Preservation Max Holding
Time
Turbidity P or G Analyse ASAP, keep in dark &
refrigerate
48 hrs
Conductivity P or G Refrigerate 1 months
Solids P or G Refrigerate 1 week

18. Chemical Parameters
Determination Container Preservation Max Holding
Time
pH P or G Analyse immediately 0.25 hrs
DO P or G Read in the field 0.25 hrs
Alkalinity P or G Refrigerate 14 d
G Fix oxygen then store in dark 8 hrs
Chloride P or G None 1 month
Fluoride P or G None 1 month
Hardness P or G Acidify with HNO3 or H2SO4, pH < 2 6 months
Sulphates P or G Refrigerate 1 month
Nitrates P or G Analyse immediately, refrigerate 48 hrs

19. Biological Parameters
Determination Container Preservation Max Holding Time
E Coli Sterile sample
bottle
Analyse within 6 hrs or store at
temp < 40C
30 hrs

20. WHO Guidelines
 A guideline value represents the concentration of a chemical that does not result in any significant risk
to health over a lifetime of consumption.
 The WHO Guidelines are determined based on the tolerable daily intake (TDI) of a chemical.
 TDI is an estimate of the amount of a chemical in food and drinking water, expressed on a body weight
basis (milligram or microgram per kilogram of body weight), that can be ingested over a lifetime without
significant health risk, and with a margin of safety (WHO,2011).
 The WHO Guidelines do not include some chemicals such as iron, calcium, sodium, magnesium and
zinc. This is because these chemicals pose no health risk at the levels generally found in drinking water.

21. Priority Chemical Parameters
Source of Chemicals Examples Common Chemicals
Naturally occurring Rocks and soils Arsenic, chromium, fluoride, iron,
manganese, sodium, sulfate,
uranium
Industrial sources and human
activities
Mining, manufacturing and
processing industries, sewage solid
waste, urban runoff, fuel leakages
Nitrate, ammonia, cadmium,
cyanide, copper, lead, nickel,
mercury
Water treatment Water treatment chemicals, piping
materials
Aluminium, chlorine, iodine, silver
Pesticides used in water for public
health
Larvicides used to control insect
vectors of disease.
Organophosphorus compounds
(e.g., chlorpyrifos, diazinon,
malathion) and carbamates (e.g.,
aldicarb, carbaryl, carbofuran,
oxamyl)

22. Potential Health Effects of Various Chemicals in Drinking
Water
Chemical Potential Health Effect from
Drinking Water
Source
Chloride No health based guideline is
proposed.
However, more than 250 mg/L of
chloride in drinking water can cause a
strong taste.
Chloride in drinking water comes from
natural sources, sewage, industrial
effluents, and from urban runoff
containing de-icing salt. Main source
of human exposure is the addition of
salt to food.
Chlorine Effects are not likely to occur at levels
of chlorine that are normally found in
the
environment. High dose of chlorine
irritates the skin, the eyes, and the
respiratory system.
Produced in large amounts and widely
used
industrially and domestically as an
important disinfectant and bleach.
(Adapted from WHO, 2011)

23. Potential Health Effects cont…
Chemical Potential health effects Source
Nitrate and
Nitrite
Long exposure may result in increased
heart rate, nausea, headaches and
abdominal pain. Main health concern is
methaemoglobinaemia, or blue baby
syndrome, that occurs in infants that are
usually bottle fed. Symptoms include
shortness of breath and their skin turning
blue due to the lack of oxygen.
Naturally occurring as part of the nitrogen
cycle. Nitrate is used in fertilizers and
sodium nitrite is a food preservative.
Concentration of nitrate in groundwater
and surface water is caused by agricultural
runoff; leaching from septic tanks, and
sewage. Nitrite is from microbial activity
and may be intermittent.
Ammonia Ammonia in drinking water is not of
immediate health concern. No health based
guideline is proposed. However, ammonia
can impact disinfection efficiency, cause
nitrite to form in distribution systems,
cause the failure of filters for removing
manganese, and cause taste and odour
problems.
Sewage, industrial processes, and
agricultural activities. Ammonia in water is
an indicator of possible bacterial, sewage,
and animal waste pollution.
(Adapted from WHO, 2011)

24. Water is life