| Indian Standards of Drinking Water |
The Bureau of Indian Standards has defined the level of solvents for safety purposes. The table below gives the common solvents in water and the permitted levels.
| Substance/ Test |
Unit |
Desirable Limit |
Maximum Permissible Limit* |
| Physical Turbidity |
NTU |
5 |
10 |
| Chemical pH |
Number |
6.5-8.5 |
No relaxation |
| Hardness |
As( CaCo)mg/l |
300 |
600 |
| Chloride |
(asCl)mg/l |
250 |
1000 |
| Iron |
(as Fe)mg/l |
0.3 |
1.0 |
| Nitrate |
(as No)mg/l |
45 |
No relaxation |
| Fluoride |
(as F) mg/l |
1.0 |
1.5 |
| Residual Chlorine |
Mg/l |
0.2-0.5 |
No relaxation |
| Arsenic |
(as A)mg/l |
0.05 |
No relaxation |
| Bacteriological Coliforms |
MPN/100ml |
10** |
No relaxation |
| E Coli |
MPN/100ml |
0 |
No relaxation |
* When there is no alternative source for drinking.
** Colitone organisms should not be detectable in 100ml of any two consecutive samples.
