Water Standards

Physical Standards
Sl. Characteristics Acceptable* Cause for Rejection*
i) Turbidity (units on J.T.U. scale) 2.5 10
ii) Colour (units on platinum-cobalt scale) 5.0 25
iii) Taste and odour Unobjectionable Unobjectionable
Chemical Standards
Sl. Characteristics Acceptable* Cause for Rejection*
7.0-8.5 6.5-9.2
Total dissolved solids (mg/l)
500 1500
Total hardness (as CaCo3) (mg/l)
200 600
Chlorides (as Cl) (mg/l)
200 1000
Sulphates (as So4) (mg/l)
200 400
Fluorides (as F) (mg/l)
1.0 1.5
Nitrates (as No3) (mg/l)
45 45
Calcium (as Ca) (mg/l)
75 200
Magnesium (as Mg) (mg/l)
>30 (If there are 250 mg/l of sulphates, Mg content can be increased to a maximum of 125 mg/l with the reduction of sulphates at the rate of 1 unit per every 2.5 units of sulphates) 150
Iron (as Fe) (mg/l)
0.1 1.0
Manganese (as Mn) (mg/l)
0.05 0.5
Copper (as Cu) (mg/l)
0.05 1.5
Zinc (as Zn) (mg/l)
5.0 15.0
Phenolic compounds (as phenol) (mg/l)
0.001 0.002
Anionic detergents (as MBAS) (mg/l)
0.2 1.0
Mineral oil (mg/l)
0.01 0.3
Arsenic (as As) (mg/l)
0.05 0.05
Cadmium (as Cd) (mg/l)
0.01 0.01
Chromium (as hexavalent Cr) (mg/l)
0.05 0.05
Cynides (as CN) (mg/l)
0.05 0.05
Lead (as Pb) (mg/l)
0.1 0.1
Selenium (as Se) (mg/l)
0.01 0.01
Mercury (total as Hg) (mg/l)
0.001 0.001
Polynuclear aromatic hydrocarbons (PAH) (µg/l)
0.2 0.2
Gross alpha activity (pCi/l)
3 3
Gross beta activity (pCi/l)
30 30

Note 1 - The figures indicated under the column 'acceptable' are the limits up to which the water is generally acceptable to the consumers.
ote 2 - It is possible that some mine and spring waters may exceed these radio activity limits and in such cases it is necessary to analyze the individual radionuclides in order to assess the acceptability or otherwise for public consumption.
* Figures in excess of those mentioned under 'acceptable' render the water not acceptable, but still may be tolerated in the absence of alternative and better source up to the limits indicated under column 'cause for rejection' above which the supply will have to be rejected.

Bacteriological Standards

i) Water entering the distribution system in piped supply chlorinated or otherwise disinfected shall satisfy the following criteria:

  • Coliform count in any sample of 100 ml should be zero. A sample of the water entering the distribution system that does not conform to this standard calls for an immediate investigation into both the efficacy of the purification process and the method of sampling.

ii) Water in the distribution system shall satisfy these three criteria.

  • E.Coli count in 100 ml of any sample should be zero.
  • Coliform organisms not more than 10 per 100 ml shall be present in any sample.
  • Coliform organisms should not be detectable in 100 ml of any two consecutive samples or more than 50 percent of the samples collected for the year.

iii) In individual or small community supplies E.Coli count should be zero in any sample of 100 ml and coliform organisms should not be more than 3 per 100 ml. If coliforms exceed 3 per 100 ml, the supply should be disinfected.

Virolological Standards

0.5 mg/l of free residual chlorine for one hour is sufficient to inactivate virus, even in water that was originally polluted. This free chlorine residual is to be insisted in all disinfected supplies in areas suspected of endemicity of infectious hepatities to inactivate virus and also bacteria. 0.2 mg/l of free residual chlorine for half an hour should be insisted for other areas.