| Sl. No. | Substance or Characteristics | Requirement Desirable Limit | Undesirable Effect Outside the Desirable Limit | Desirable/ Essential | Remarks |
|---|---|---|---|---|---|
| 1. | Colour, Hazen Units, Max. | -- | Above 10 | Essential | May be extended to 50 only if toxic substances are not suspected in absence of alternative sources. |
| 2. | Odour | Objectionable | -- | Essential | a)Test cold and when heated. b)Test at severaldilutions. |
| 3. | Taste | Agreeable | -- | Essential | Test to be conducted only after safety has been established. |
| 4. | Turbidity, NTU, Max. | 10 | Above 10, Consumer acceptance decreases. | Essential | May be extended upto 25, in absence of alternative sources. |
| 5. | pH Value | 6.5 to 8.5 | Beyond this range the water will affect the mucous membrane and/or water supply system. | Essential | May be relaxed upto 9.2 in absence of alternative sources. |
| 6. | Total Hardness (as CaCO3) mg/l Max. | 300 | Encrustation in water supply structure and adverse effects on domestic use. | Essential | May be extended upto 600 in the absence of other sources. |
| 7. | Calcium (as Ca), mg/l, Max. | 75 | Encrustation in water supply structure and adverse effects on domestic use. | Desirable | May be extended upto 200, in the absence of other sources. |
| 8. | Magnesium (as Mg), mg/l, Max. | 30 | Encrustation in water supply structure and adverse effects on domestic use. | Desirable | May be extended upto 100, in the absence of other sources. |
| 9. | Copper (as Cu), mg/l, Max. | 0.05 | Astringent taste, dis-colouration and corrosion of pipes fittings and utensils will be caused beyond this. | Desirable | May be relaxed upto 1.5. |
| 10. | Iron (as Fe), mg/l, Max. | 0.3 | Beyond this limit taste/appearance are affected & has adverse effect on domestic uses and water structures, and promotes iron bacteria | Essential | May be extended upto 1.0 in absence of alternative sources. |
| 11. | Manganese (as Mn), mg/l, Max. | 0.1 | Beyond this limit, taste/appearance are affected on domestic uses and water supply structure. | Desirable | May be extended up to 0.5 where alternate source is not available. |
| 12. | Sulphate (as SO4), mg/l, Max. | 250 | Beyond this causes gastrointestinal irrigation when magnesium of sodium are present . | Essential | May be extended up to 400 provided magnesium (as Mg) does not exceed 30. |
| 13. | Chloride (as Cl), mg/l, Max. | 250 | Beyond this limit, taste, corrosion and palatability are affected | Essential | May be extended up to 1000 in the absence of other alternate sources. |
| 14. | Nitrate (as NO3)mg/l, Max. | 45 | Beyond this mathemoglobinaemia takes place. | Desirable | No relaxation |
| 15. | Fluoride (as F), mg/l | 0.6 to 1.2 | Low floride level are linked with dental carries above 1.5 it may cause fluorosis. | Desirable | If the limit is below 0.6 water source should be rejected but suitable public health measures should be taken.Maximum limit may be extended to 1.5 if no better alternate source is available. |
| 16. | Phenolic Compounds (as C6H5OH), mg/l, Max. | 0.001 | Beyond this it may cause objectionable taste and odour. | Desirable | May be relaxed up to 0.002. |
| 17. | Mercury (as Hg) mg/L, Max. | 0.001 | Beyond this the water becomes toxic. | Desirable | No relaxation of this limit is allowed to be tested when pollution is suspected. |
| 18. | Cadmium (as Cd), mg/l, Max. | 0.01 | Beyond this the water becomes toxic. | Desirable | No relaxation of this limit is allowed to be tested when pollution is suspected. |
| 19. | Selenium (as Se) mg/l, Max. | 0.01 | Beyond this the water becomes toxic. | Desirable | No relaxation of this limit is allowed to be tested when pollution is suspected. |
| 20. | Arsenic (as as) mg/l, Max. | 0.05 | Beyond this the water becomes toxic. | Desirable | No relaxation of this limit is allowed to be tested when pollution is suspected |
| 21. | Cyanide (as Cn) mg/l, Max. | 0.05 | Beyond this the water becomes toxic. | Desirable | No relaxation of this limit is allowed to be tested when pollution is suspected |
| 22. | Lead (as Pb), mg/l, Max. | 0.1 | Beyond this the water becomes toxic. | Desirable | No relaxation of this limit is allowed to be tested when pollution is suspected |
| 23. | Zinc (as Zn), mg/l, Max. | 5.0 | Beyond this limit it can cause astringent taste and an opalescence in water. | Desirable | May be relaxed up to 10.0. To be tested when pollution is suspected. |
| 24. | Anionic detergents (as MBAS), mg/l, Max. | 0.2 | Beyond this limit it can cause a light froth in water. | Desirable | May be relaxed up to 1.0. To be tested when pollution is suspected. |
| 25. | Chromium (as Cr+6) mg/l, Max. | 0.05 | May be carcinogenic. | Desirable | -- |
| 26. | Mineral Oil, mg/l, Max. | 0.01 | Beyond this limit undesirable taste and odour after chlorination takes place. | Desirable | May be relaxed up to 0.03. To be tested when pollution is suspected |
| 27. | Residual free chlorine mg/l, Max. | 0.2 | -- | Essential | To be applicable only when water is chlorinated. Tested at consumer end. When protection against viral infection is required, it should be min. 0.5 mg/L. |