Water and water quality standards. Disnfection of drinking water. Water quality surveillance. Removal of hardness of water. Purification of water.

1. WATER & WATER
QUALITY
STANDARDS
DR VINOD RATHOD
SMO/HQ/SWR
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2. LESSON PLAN
• INTRODUCTION
• SAFE & WHOLESOME WATER
• USES OF WATER
• SOURCES OF WATER
• WATER POLLUTION
• PURIFICATION OF WATER
• WATER QUALITY STANDARDS
• DRINKING WATER QUALITY SURVEILLANCE
• HARDNESS OF WATER
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3. INTRODUCTION
• Water is essential to sustain life, and a satisfactory (adequate,
safe and accessible) supply must be available to all.
• Improving access to safe drinking-water can result in tangible
benefits to health.
• Every effort should be made to achieve drinking-water that is as
safe as practicable.
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4. SAFE & WHOLESOME WATER
• FREE FROM PATHOGENIC AGENTS
• FREE FROM HARMFUL CHEMICAL SUBSTANCES
• FREE FROM COLOUR
• FREE FROM ODOUR
• PLEASANT TO TASTE
• USABLE FOR DOMESTIC PURPOSES
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5. USES OF WATER
• DOMESTIC PURPOSES
• PUBLIC PURPOSES
• INDUSTRIAL PURPOSES
• AGRICULTURAL PURPOSES
• POWER GENERATION
• CARRYING AWAY WASTES
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6. SOURCES OF WATER SUPPLY
1. RAIN WATER
2. SURFACE WATER
- IMPOUNDING RESERVOIR
- RIVERS AND STREAMS
- TANKS, PONDS & LAKES
3. GROUND WATER
- SHALLOW WELLS
- DEEP WELLS
- SPRINGS
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7. WATER POLLUTION
• Pure uncontaminated water is not present in nature.
• Impurities Natural
Man-made
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8. NATURAL IMPURITIES
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9. MAN-MADE IMPURITIES
• SEWAGE
• INDUSTRIAL & TRADE WASTES
• AGRICULTURAL POLLUTANTS
• PHYSICAL POLLUTANTS
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10. WATER RELATED DISEASES
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11. PURIFICATION OF WATER
• LARGE SCALE
- STORAGE
- FILTRATION
- DISINFECTION
• SMALL SCALE
- HOUSEHOLD PURIFICATION
- DISINFECTION OF WELLS
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Slow Sand Filter
Rapid Sand Filter

12. SLOW SAND FILTER
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13. Monday, May 16, 2022 13

14. DISINFECTION
For a chemical or an agent to be a potentially useful as a
disinfectant in water supplies, it has to satisfy following criteria:
1. Capable of destroying pathogenic organisms
2. No toxic by-products
3. Available at reasonable cost
4. Safe for application
5. Able to leave residual concentration
6. Amenable to detection
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15. CHLORINATION
Chlorine:
• Kills pathogenic bacteria
• Oxidizes iron, manganese and Hydrogen sulfide
• Controls algae and slime constituents
• No effect on spores and certain viruses.
• Acts best at a ph of 7.
• Hypochlorous acid (HOCl) is the most effective form of chlorine for
disinfection.
• H2O + Cl2 HCl + HOCl
HOCl H+ + OCl-
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16. PRINCIPLES OF CHLORINATION
1. Water should be free from turbidity.
2. Chlorine demand of water should be estimated.
“The chlorine demand of water is the difference between the
amount of chlorine added to the water, and the amount of
residual chlorine remaining at the end of a specific period of
contact (usually 60 minutes), at a given temperature and ph of
the water”.
The point at which this demand is met is called “break-point”.
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17. CONTINUED….
3. Contact period – the presence of free residual chlorine for a
contact period of at-least one hour is essential to kill bacteria and
viruses.
4. Minimum recommended concentration of free chlorine is 0.5
mg/L for one hour.
5. Chlorine demand + free residual chlorine = correct dose of
chlorine to be applied.
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18. METHOD OF CHLORINATION
1. Bleaching powder (CaOCl2)
- Contains 33% available chlorine.
- Should be stored in a cool, dry, dark place.
- Chlorine solution may be prepared from bleaching powder
- Horrock’s apparatus may be used for estimating dose of
bleaching powder.
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19. HORROCK’S APPARATUS
CONTENTS:
a. 6 WHITE CUPS (200 ML CAPACITY)
b. ONE BLACK CUP WITH CIRCULAR MARK ON THE INSIDE
c. 2 METAL SPOONS (EACH HOLD 2 G)
d. 7 GLASS STIRRING RODS
e. 1 SPECIAL PIPETTE
f. 2 DROPPERS
g. STARCH-IODIDE INDICATOR SOLUTION
h. INSTRUCTION FOLDER
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20. Procedure:
a. 2 g powder in black cup. Add water and make thin paste. Add more
water up to the mark with vigorous stirring. Allow to settle. This is
‘stock solution”.
b. Fill the 6 cups with water to be tested.
c. Using pipette add 1 drop of stock solution to 1st cup, 2 drops to 2nd
cup and so on.
d. Stir water in each cup using separate rod
e. Wait for ½ hour.
f. Add 3 drops of indicator and stir again.
g. First cup to develop distinct blue colour determines the dose of
bleaching powder.
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21. For eg: if 3rd cup shows blue colour, then 3 level spoonfuls
i.e., 6 grams of bleaching powder would be required to
disinfect 455 litres of water.
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22. ORTHOTOLIDINE TEST (OT)
• Easily determine free and combined chlorine in water.
• Analytical grade Orthotolidine, dissolved in 10% hydrochloric acid
is used.
• 0.1 ml of reagent added to 1 ml of water. When added to water
containing chlorine, it turns yellow.
• Compare with standard colour.
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23. • READ WITHIN 10 SECONDS – DETERMINES FREE
CHLORINE.
• IF READ AFTER 15-20 MINUTES – DETERMINES COMBINED
CHLORINE
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24. ORTHOTOLIDINE-ARSENITE
(OTA) TEST
• Free and combined chlorine can be determined separately.
• Nitrites, Iron, Manganese also produce yellow colour with OT test
which can be overcome with OTA test.
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25. 2. CHLORINE GAS
First choice for urban water supplies. Applied using
chlorinating equipment.
Eg: Paterson’s Chloronome
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26. 3. HIGH TEST HYPOCHLORITE (HTH)
60 – 70% available chlorine. Not used nowadays.
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27. 4. CHLORINE TABLETS
- Available in tablet form
- May be used for small scale purification.
- Used in emergency situations
- Dose – 0.5g for 20 litres of water
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28. Monday, May 16, 2022 28

29. REVERSE OSMOSIS
• Process of forcing the solvent (water with higher concentration)
by applying pressure across a semi-permeable membrane is
called reverse osmosis.
• Pressure range used is 15-50 bar.
• Membrane pore size is < 0.002 μm.
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30. WATER QUALITY STANDARDS
I. ACCEPTABILITY ASPECTS
II. MICROBIOLOGICAL ASPECTS
III. CHEMICAL ASPECTS
IV. RADIOLOGICAL ASPECTS
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31. ACCEPTABILITY ASPECTS
A. Physical parameters
1. Turbidity – on aesthetic grounds
- should be < 1 NTU
2. Colour – organic & inorganic substances may cause colour.
- should be < 15 TCU
3. Taste & odour – from natural and biological reasons.
- should be acceptable
4. Temperature – should be acceptable
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32. B. INORGANIC CONSTITUENTS
1. Chlorides – alters taste and may cause corrosion. Should be < 250
mg/L
2. Hardness – should be within 100 – 200 mg/L. Less than 100
causes corrosion whereas, more than 200 causes scale formation
3. Ammonia – alters taste and odour, reduces disinfection. Up to 1.5
mg/L.
4. pH – low pH causes corrosion, high pH alters taste (soapy). Ideal
is 6.5 to 8.5
5. Hydrogen sulphide – alters taste and odour. Up to 0.05 mg/L.
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33. 6. Iron – causes staining of laundry and sanitary ware. Up to 0.3
mg/L
7. Sodium – alters taste. Up to 200 mg/L
8. Sulphate – alters taste, may cause corrosion. Up to 250 mg/L
9. Total dissolved solids – alters taste, causes scaling. Up to 1000
mg/L
10. Zinc – alters taste and appearance. Up to 4 mg/L
11. Manganese – staining laundry, alters taste. Up to 0.4 mg/L
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34. 12. Dissolved oxygen – no guideline value but depletion causes
alteration in taste and smell.
13. Copper – staining laundry, corrosion. Up to 2 mg/L.
14. Aluminium – causes discoloration and may produce deposits.
Up to 0.2 mg/L
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35. MICROBIOLOGICAL ASPECTS
(A) Bacteriological indicators:
- Coliform organisms – indicative of fecal contamination of water.
Must not be detectable in water.
- Fecal streptococci – indicative of recent contamination of water.
Must not be detectable.
- Cl. Perfringens – indicative of remote contamination of water.
Must not be detectable.
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36. Monday, May 16, 2022 36

37. (B) VIROLOGICAL ASPECTS:
- Water should be free from any viruses infective to man.
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38. (C) BIOLOGICAL ASPECTS:
- Protozoa viz., Entamoeba histolytica, Giardia spp and rarely
Balantidium coli. Should not be present in water supply.
- Helminthic larvae or eggs should not be present in the water supply.
- Free living organisms like Fungi and Algae causes alteration in taste,
odour and hinders operation of water treatment processes.
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39. CHEMICAL ASPECTS
a. INORGANIC CONSTITUENTS
a. ORGANIC CONSTITUENTS
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40. a. INORGANIC CONSTITUENTS
1. Arsenic: enters through industrial effluents, soil erosion. Max limit
is 0.01 mg/L.
2. Cadmium: enters through metal pipes, industrial effluents,
fertilizers. Max limit is 0.003mg/L.
3. Chromium: enters through soil. Max limit is 0.05mg/L.
4. Fluoride: enters through soil, fertilizers. Max limit is 1.5 mg/L.
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41. 5. Lead: enters through plumbing systems. Max limit is 0.01 mg/L.
6. Mercury: enters through soil. Max limit is 0.006 mg/L.
7. Nitrate & Nitrite: enters through soil and farming practices. Max limit
for nitrate(NO3) is 50 mg/L and for nitrite(NO2) is 3 mg/L. But, they
both should be considered simultaneously for quality check, hence
guideline values are needed and the ratio of the guideline values
should be < 1.
8. Selenium: enters through soil. Max limit is 0.04 mg/L.
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42. B. ORGANIC CONSTITUENTS:
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43. PESTICIDES:
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44. RADIOLOGICAL ASPECTS
Proposed guideline value for radioactivity of water is:
a. GROSS ALPHA ACTIVITY – 0.5 BQ/L
b. GROSS BETA ACTIVITY – 1.0 BQ/L
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45. SURVEILLANCE OF DRINKING
WATER QUALITY
1. SANITARY SURVEY
2. SAMPLING
3. BACTERIOLOGICAL SURVEILLANCE
4. BIOLOGICAL EXAMINATION
5. CHEMICAL SURVEILLANCE
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46. SANITARY SURVEY
• ON-THE-SPOT INSPECTION AND EVALUATION
• TO DETECT AND CORRECT FAULTS AND DEFICIENCIES
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47. SAMPLING
• Should be done with aseptic precautions.
• Competent and trained personnel should do it.
• 2 types of sample collected –
(a) for physical and chemical analysis
(b) for bacteriological examination.
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48. FOR PHYSICAL & CHEMICAL
EXAMINATION
• Winchester quart bottles may be used.
• Capacity should not be less than 2 litres.
• Before collecting the sample rinse the bottle three times with the
same water and then fill it with water.
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49. FOR BACTERIOLOGICAL
EXAMINATION
• Use clean sterilized bottles of 200-250 ml capacity.
• For chlorinated water, 0.1 ml of 3% solution of Sodium
thiosulphate should be added to the bottles before sterilizing it.
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50. (1) COLLECTION FROM TAP
• Open the tap fully, let the water run for 2 minutes.
• Without touching the mouth of the bottle, collect the water from
gentle stream.
• Seal the bottle.
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51. (2) COLLECTION FROM RIVERS,
LAKES, RESERVOIRS, WELLS
ETC.
• Should not be too near the bank, not far from draw point.
• Lower the bottle under the surface of water using a clean string
and collect the sample.
• Or, hold the bottle by the bottom and plunge its neck down-wards
below the surface of water, tilt it slightly up-wards and collect the
sample.
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52. (3) TRANSPORT & STORAGE OF
SAMPLES
• Should be sent to laboratory immediately.
• If the laboratory is far, then the sample should be kept in ice and
transported within 48 hrs.
• Details such as date and time of collection, recent rainfall,
sanitary survey should accompany the sample.
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53. TESTS IN LABORATORY
• Includes tests for E. Coli, Cl. perfringens and Fecal streptococci.
(1) Presumptive Coliform test
(I) Multiple Tube Method: inoculate samples of water(0.1, 1.0, 10,
50 ml) into McConkey’s Lactose Bile Salt Broth with
Bromocresol purple as indicator. Incubate for 48 hrs. From the
number of tubes showing acid and gas, an estimate of the
MPN (most probable number) of Coliform organisms in 100 ml
of water can be obtained by statistical tables. This is know as
Presumptive Coliform test.
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54. CONFIRMATORY TEST: Required in cases of chlorinated water.
Subculture each presumptive positive tube in 2 tubes of brilliant
green bile broth.
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Incubate at 37º
C for 48 hrs
Incubate at 44º
C for 06 and 24
hrs
Coliform present E. Coli present
Indole
production test
at 44º C
E. Coli
confirmed

55. (II) MEMBRANE FILTRATION TECHNIQUE:
Sample is filtered through cellulose ester membrane. This
membrane is inoculated in suitable media for 20 hrs and
results are read.
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56. (2) COLONY COUNT
- On Nutrient agar at 37º C and 22º C.
- Number of colonies formed are counted.
- Sudden increase in colony count is the earliest indicator of
contamination
- Recommended plate counts are given below:
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Water at the
point of
consumption
Plate count after
2 days at 37º C
Plate count after
3 days at 22º C
Disinfected 0 20
Not-disinfected 10 100

57. BIOLOGICAL EXAMINATION
• For microscopic organisms
• Eg; Algae, Fungi, Yeast, Protozoa, Rotifers, Crustaceans, minute
worms etc
• Index of pollution of water.
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58. CHEMICAL SURVEILLANCE
• Tests for pH, colour, turbidity
• Tests for inorganic, organic constituents and radioactivity of
water.
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59. HARDNESS OF WATER
• Soap destroying power of water
• Expressed in Meq/L
• Main culprits:
- Calcium bicarbonate [Ca(HCO3)2]
- Magnesium bicarbonate [Mg(HCO3)2]
- Calcium sulphate [CaSO4]
- Magnesium sulphate [MgSO4]
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60. CLASSIFICATION OF HARDNESS IN WATER
- DRINKING WATER SHOULD BE MODERATELY HARD.
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Classification Level of hardness (mEq/L)
(a) Soft Water < 1 (<50 mg/L of CaCO3)
(b) Moderately hard 1 – 3 (50 - 150mg/L of CaCO3)
(c) Hard Water 3 – 6 (150 – 300 mg/L of CaCO3)
(d) Very hard water > 6 (> 300 mg/L of CaCO3)

61. REMOVAL OF HARDNESS
(A) Temporary hardness (carbonate)
- Due to bicarbonates
- Removal by (i) Boiling
(ii) Addition of Lime
(iii) Addition of Sodium carbonate
(iv) Permutit process
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62. (B) PERMANENT HARDNESS (NON-CARBONATES)
- Due to sulphates
- Removal by (i) Addition of Sodium carbonate
(ii) Permutit process
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63. (i) BOILING
- Expensive method
- Removes carbon dioxide and precipitates Calcium
carbonate
Ca(HCO3)2 CaCO3 + H2O + CO2
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64. (II) ADDITION OF LIME
- Clark’s method
- Lime absorbs carbon dioxide and precipitates Calcium
carbonate
Ca(OH)2 + Ca(HCO3)2 2CaCO3 + 2H2O
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65. (III) ADDITION OF SODIUM CARBONATE
- Removes both temporary and permanent hardness
a. Na2CO3 + Ca(HCO3)2 CaCO3 + 2NaHCO3
b. Na2CO3 + CaSO4 CaCO3 + Na2SO4
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66. (IV) PERMUTIT PROCESS
- Removes both temporary and permanent hardness.
- Also called Base exchange process
- Sodium permutit (Na2Al2Si2OH2O) is added in large water
supplies.
- Ca and Mg ions are replaced by Na ions.
- Ca and Mg permutits are precipitated.
- Zero hardness is achieved.
- Further, small quantities of hard water is added to retain
some hardness.
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