3. The WHO published guideline for drinking water
quality.
Its implementation ensures safety of drinking water
supplies.
Guidelines for drinking water quality recommended
by WHO (2011) relate to :
I. Acceptability aspects
II. Microbiological aspects
III. Chemical aspects
IV. Radiological aspects
3
5. Turbidity
Drinking water should be free from turbidity.
Interferes with disinfection and microbiological
determination.
Acceptable level - turbidity of less than 4 NTU
Measured with Turbidity meter
5
7. Drinking water should be free from colour .
Organic matter, iron , manganese , industrial waste
etc.
The guideline value - 15 true colour units (TCU).
7
8. Develop due to contamination by chemicals.
Storage and distribution.
Indicative of pollution or malfunction during water
treatment or distribution.
8
9. Low water temperature
Decrease the efficiency of treatment process.
High water temperature
Enhances the taste, odour .
Corrosion problem may increase.
No guideline value is recommended.
9
10. All water including rain water contain chlorides.
Standard level for chloride - 200 mg/ litre .
Maximum permissible level - 600 mg/ litre
Measured by spectrophotometer or titration method.
Spectrophotometer
10
11. Taste threshold for calcium ion - 100-300 mg/ litre .
Excessive soap consumption and scum formation.
Forms deposits of calcium carbonate scale on
heating.
Soft water : low buffer capacity ,corrosive for water
pipes.
Measured by titration method.
11
13. Ammonia originates from metabolic, agricultural and
industrial processes and from disinfection with
chloramine .
Natural levels - below 0.2 mg/ litre
Anaerobic ground water contains 3mg/ litre
Its presence indicates pollution by bacteria , sewage
or animal waste.
13
14. pH< 7 causes severe corrosion
Acceptable range - 6.5 to 8.5.
Measured with pH meter
14
15. Acceptable limits- 0.05-0.1 mg/l
Gives rotten egg odour (stagnant water)
Iron
On exposure to atmosphere ferrous iron oxidises to
ferric ion
Gives reddish brown colour to water
Deposit slimy coating on pipes
Sodium
Measured with Flame photometer.
Average taste threshold for sodium - 200 mg/ l
15
17. Important effect on taste of water
Acceptability levels of TDS -<1000mg/litre
Excessive levels cause scaling of boilers , pipes
Zinc
Gives undesirable astringent taste
Zinc content >5mg/litre gives opalescent look and
greasy film on boiling
Manganese
Acceptable levels-<0.1mg/litre
Excess Mg stains sanitary ware and laundry
17
18. Increases corrosion of steel fittings
Concentration >1mg/litre cause staining of laundry and
sanitary ware
Aluminium
Concentration >0.2mg/l leads to deposition Aluminium
hydroxide floc.
18
20. Coliform organisms-
Present in human intestine
Presence indicates faecal contamination
Faecal streptococci-
Occur in faeces
Confirmatory evidence of recent faecal
contamination
Cl.perfringens –
Resist chlorination
Presence suggest faecal contamination
20
21. Coliforms - Faecal groups -E coli
Non Faecal – Klebsiella aerogens
Why coliforms?
Coliforms are abundant in intestine(200-400billion/day)
Easily detected by culture
Survive longer than other pathogens
Greater resistance to forces of natural purification
21
22. ORGANISMS GUIDELINE VALUE
All water intended for drinking Must not be detectable in any
100ml sample
Treated water entering
distribution system
(E.coli ,total coliform count)
Must not be detectable in any
100ml sample
Treated water entering
distribution system
(E.coli ,total coliform count)
Must not be detectable in any
100ml sample
In c/o large supplies, must not
be present in 95% of samples
taken throughout any 12month
period
22
23. Free from virus
Disinfect with 0.5 mg/ml of free chlorine
residual after contact period of at least 30
minutes at pH 8.(Hep A)
Others need 0.2 mg/ml
Criteria
Ozone :0.2-0.4 mg/ml for 4 minutes
23
24. Protozoa-
E.histolytica , Balantidium coli
Helminths-
Infective form of round worm, hook worm
dracunculus medinensis , schistosomes
Free living-
fungi ,algae interfere with water treatment
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31. PAH and turbidity
Restriction on coal tar based lining in storage tanks
Source of contamination should be identified
31
32. Radioactivity should be as low as possible
Guideline values-
Gross alpha activity-0.5 Bq /L
Gross beta activity- 1.0 Bq /L
1Bq= 1 disintegration per second
32
37. Identify & evaluate factors associated with drinking
water which could pose a health risk
To take both preventive & remedial action
For development of rational strategies for improvement
of quality of water supply services
To meet agreed national standards & institutional targets
37
39. Approval of new sources(Including private owned)
Watershed protection
Approval-construction & operating procedures of water
works
disinfection of the plant & distribution system
periodic flushing programmes & cleaning of
water storage facilities
certification of operators
regulation of chemical substances
Cross-connection control ,back flow
prevention ,leak detection control 39
40. Sanitary surveys
Monitoring programmes
Development of codes of practice for well
construction ,pump installation and plumbing
Inspection quality control in bottled water
40
42. A sanitary survey defined as
“an on-site inspection and evaluation by a qualified
person of all the conditions, devices, and practices in
the water supply system which pose a danger to the
health and well being of the water consumer ”
42
43. A new source is being contemplated
Laboratory analysis indicates hazard to health
An outbreak occurs
To interpret bacteriological, chemical and physical
analyses of samples
When any change takes place that can affect the
water system, e.g. industries coming up in watershed
and
On a regular basis
43
44. Ensure no external contamination
Asepsis Glass bottles with securely fitting stoppers
or caps with non toxic liners.
Sample for general analysis= 2 litres(non-acidified)
Bacteriological analysis=250 ml (sterilized bottle)
Metals analysis=1000 ml (acidified sample)
44
52. Take the positive tube from the presumptive test
Incubate one plate at 37°C for 24 hours and
another at 44.5°C for 24 hours.
Look for typical colonies in the media ; blue
black with green metallic sheen colonies are of E.
coli
52
54. Nutrient agar at 37 deg C and 22 deg C
An estimate of the general bacterial purity of water.
Same source at frequent intervals may be of
considerable value.
A sudden increase in the colony count may give the
earliest indication of contamination.
54
55. The recommended plate counts are
Water at the point
of consumption
Plate count after 2
days at 37 deg C
Plate count after 3
days at 22 deg
( i ) Disinfected 0 20
(ii) Not - disinfected 10 100
55
56. The National Rural Drinking Water Quality
Monitoring & Surveillance Programme was
launched in February 2006 (2005-06)
Institutionalization of community participation and
involvement of PRIs for water quality monitoring &
surveillance of all drinking water sources
Jal surakshak
56
57. Park K. Textbook of preventive and social medicine. 22nd ed.
Jabalpur (India): Bhanot publishers; 2009. p. 667-78.
WHO - Guidelines for Drinking-water quality: surviellance &
control of community supplies. Vol.3, Recommendations. –
3rd ed.
Uniform Drinking Water Quality Monitoring Protocol: Govt
Of India, Ministry of Drinking Water and Sanitation ; Feb
2013
http://www.mdws.gov.in/wqms
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