Water quality standards are defined based on analyzing raw water characteristics including physical, chemical and bacteriological properties. Turbidity, pH, hardness, iron and bacteria such as coliform and E.coli are measured against standards for drinking water. The presence of pathogens is tested by counting coliform forms, which indicate whether water may contain harmful bacteria if coliforms are found. Water treatment processes are used to make water potable by removing contaminants and disinfecting water to destroy pathogens.

1. Water Supply and
Quality Management
MD MOUDUD HASAN
LECTURER
DEPARTMENT OF AGRICULTURAL AND INDUSTRIAL ENGINEERING
FACULTY OF ENGINEERING
HAJEE MOHAMMAD DANESH SCIENCE AND TECHNOLOGY
UNIVERSITY
DINAJPUR

2. Definition

3. Water demand
 Drinking purpose – (WHO)
• 3.7 L/day (minimum) for men
• 2.7 L/day (minimum) for women
• Other purpose – 20 L/day

4. Some factors on considering water
demand are -

5. Water Availability
 4 source

6. Water Quality and Standards
Water quality and standards are defined on the
basis of analyzing the raw water on their
physical chemical and bacteriological
characteristics.
Physical Characteristics
i) Turbidity
ii) Colour
iii) Taste and odour
iv) Temperature
v) Specific conductance

7. Water Quality and Standards
 Turbidity: If a large amount of solids are present in water it
will appear turbid in appearance.
 Turbidity depends upon the finesse and concentration of
practices present in water
 It is expressed as the amount of suspended matter in mg/L
or ppm
 Measurement
 (a) For field – Turbidity rod
 (b) For Lab –
 (i) Jackson’s turbidity meter
 (ii) Nphelometer is used for treated water. Nephelometer can measure turbidity
less than 1 ppm
 NTU – Nephlometer Turbidity unit
 The IS value for drinking water is 10 – 25 NTU

8. Water Quality and Standards
 Colour: Dissolved organic material from decaying vegetation or
inorganic materials may import colour to the water.
 The standard unit of color is that which is produce by “one mg
of platinum cobalt” dissolved in one liter of distilled water
 The IS value for treated water is 5 to 25 cobalt unit.

9. Water Quality and Standards
 Taste and Odour:
 Mostly organic and inorganic material originating from municipal or
industrial waste contribute taste and odour to the water.
 Taste and odour can be expressed in terms of odour intensity and
threshold values.

10. Water Quality and Standards
 Temperature:
 The increase in temperature decreases palatability (pleasant in taste),
because at high temperature CO2 and some other volatile gases are
expelled.
 The ideal temperature of water for drinking purpose is 5 to 120C
 Specific conductance:
 Presence of salt can be estimated by measuring specific conductivity
(unit: μmho/cm)

11. Water Quality and Standards
Chemical characteristics
i) pH
ii) Acidity
iii) Alkalinity
iv) Hardness
v) Chlorides
vi) Iron solids
vii) Nitrates

12. Water Quality and Standards
 pH: pH value denoted about the alkalinity and Baricity of the
water. It is the logarithm of the reciprocal of the hydrogen
ion concentration pH = log[1/H+]
 The values of pH for drinking water must be between 6.5 to
8.5

13. Water Quality and Standards
 Acidity: It is caused by the presence of uncombined CO2
mineral acids or salts of strong acids and weak bases. It also
salts of strong acids and weak bases. It also determines the
measures of capacity of water to neutralizes the measures
the base.
  It is expressed as mg/L in terms of CaCO3
  Desirable 200 mg/L CaCO3
 permissible limit 600 mg/L

14. Water Quality and Standards
 Hardness
 It is the characteristics of water which prevents formation of
lather or foam when mixed with the soap.
 It is usually caused by divalent ion of calcium and
magnesium ( Ca+2, Mg+2 )

15. Water Quality and Standards

16. Water Quality and Standards
 Chlorides Content
 In the form of NaCl
 Permissible limit – 250 mg/L
 Chloride concentration is detected by titrating water with
standard silver nitrate solution using kMnO4 as indicator
 Sulphates: Sulphates occur in water due to leaching from
sulphate mineral and oxidation of sulphides
 Sulphates desirable limit = 150 mg/L
 Permissible limit = 400 mg/L

17. Water Quality and Standards
 Iron: When ferric oxide comes in contact with water it
converts into ferrous bicarbonate and further it oxidieses to
ferric hydroxide ppt under favourable conditions.
 Desirable limit – 0.3 mg/L
 Permissible limit – 1.0 mg/L
 Nitrates: Nitrates in surface water occurs by leaching of
fertilizers from soil during surface runoff and nitrification of
organic matter
 Desirable limit for drinking water = 45 mg/L
 Permissible limit for drinking water = 100 mg/L
 Concentration of nitrates above 45 mg/L causes a diseases called as
blue baby disease

18. Water Quality and Standards
 Dissolved Gases
 Methane – explosive
 H2S – Bad smell
 CO2 – Indicates biological level then it indicates presence of
organic matter oxygen deficiency 5 – 8 ppm
 Minimum Dissolved oxygen foe survival fishes etc = 4 mg/L

19. Water Quality and Standards
 Bacterial and Microscopic Characteristics
 i) Aerobic Bacteria → Required oxygen for survival
 ii) Anaerobic Bacteria → Do not required dissolve O2
 iii) Facultative Bacteria → can survive with or without O2
 Through some species of bacteria one may be helpful in
cleaning of water but other pathogenic bacteria are harmful

20. Water Quality and Standards
 The presence of pathogenic bacteria can be tested by
counting presence of coil Forms
 ColiForms (Also called B coli)
 Coliforms are important harmless aerobic microorganism
which are found residing in the intestines of all warm
blooded animals including human being
 Since these harmless organism live longer in water
than the pathogenic bacteria it is generally presumed
that the water will be safe are free from pathogens if
no coliform bacteria are present in it.

21. Water Quality and Standards
 Water Borne Diseases and Their Control
 a) Disease caused by Bacterial infections
 Disease caused by
 i) Typhoid fever - salmonella typhi
 ii) Cholera - vibro – cholera
 iii) Bacillary Dysentery – shiga bacillus or Flexner - bacillus
 b) Disease cause by viral infections
 i) Hepatitis - Hepatist viral
 ii) Poliomyelitis - polio virus
 c) Disease caused by protozoal infections
 i) Amoebic Dysentry – Antoneoba histolitric germ

22. Water Quality and Standards
 Quality Standard for Industrial Water Supply
Boiled water
Hardness 1 mg/L
Pulp and paper: water should be free from iron Mn and
hardness.
 Quality Standard for Municipal Water Supply
Municipal water required for domestic uses, particularly the
water required for drinking, must be colorless odourless and
tasteless.
It should be free turbidity and excessive toxic chemical and
bacteriological characteristics of water must be in between
the desirable and permissible limit.

23. Water Treatment

24. Treatment Process

29. Water Distribution

30. Wastewater

31. Water Quality and Standards
 Measurement of coliform
 Widely used
 Filter the water through a sterile membrane of special design
porosity = 80 pore size (5 to 10 rm) and the membrane is put in
contact with nutrients (M – Endo’s medium) that will permit the
growth of only coliform colonies. This process is called culturing.
 After an incubation period of 20 hrs, the coliform organs are
developed into visible colonies which can be easily counted
Ecoli ferment lactose with gas formation with 48 hours
incubation at 350 C. Based on this E.coli density is estimated
by multiple fermentation procedure in different test. Which
consist of identification of E.coli in different dilution
combinations.

32. Water Quality and Standards
 MPN value is calculation as follows
 Five 10 ml (five dilution combinations) tube is tested for E.coli and if
out 5 only one given positive test for E.coli and all other are
negative
 The from the table we can find out the MNP value for one (+ve)
and other (-ve), which is equal to 2.2 in present case
 Coliform
 Used to measure the coliform bacteria present in water sample
 “It may be defined as the reciprocal of the smallest quantity
of a sample which would give a positive B coli test”