Parameters	Requirements (desirable limits)	Undesirable effects when taken outside the permissible limits	Permissible limit in absence of alternative source
essential feature
pH	6.5 – 8.5	Water beyond this limit will affect the mucous membrane and/or the water supply system	no rest
color (hazen units), max	6.5 – 8.5	Above 5, consumer acceptance decreases	25
‘odor	indisputable
Taste	Agree
Turbidity, NTU, Max	5	Above 5, consumer acceptance decreases	10
Total Hardness (as CaCO.)₃), Max	300 mg/L	Encroachment in water supply infrastructure and adverse effect on domestic use	600 mg/L
Iron (as Fe), Max	0.30 mg/L	Beyond this limit taste/appearance is affected, domestic uses and water supply structures are adversely affected, and iron promotes bacteria	1.0 mg/L
Cl, Max. as chloride	250 mg/L	Taste, spoilage and palatability are affected beyond this limit.	1000 mg/L
residual free chlorine, min	0.20 mg/L
desirable traits
dissolved solids, max	500 mg/l	In addition, taste is reduced and may cause gastrointestinal irritation.	2000 mg/l
Calcium (as Ca), Max	75 mg/l	Encroachment in water supply infrastructure and adverse effect on domestic use	200 mg/l
Magnesium (as Mg), Max	30 mg/l		100 mg/l
Copper (As Cu), Max	0.05 mg/l	astringent taste, discoloration and corrosion of pipes, fittings and utensils would cause beyond	1.5 mg/l
manganese mn), max	0.1 mg/l	beyond this limit taste/appearance are affected, adverse effect on home use and water supply structures	0.3 mg/l
sulfate (as therefore₄), Max	200 mg/l	beyond gastrointestinal tract jealous when Magnesium O	400 mg/l
NO. as nitrates₃	45 mg/l	Also methane-moglobinemia occurs	100 mg/l
Fluoride, Max	1.0 mg/l	Fluoride can be kept as low as possible. High fluoride can cause fluorosis	1.5 mg/l
alkalinity, max	200 mg/l	beyond this limit the taste becomes unpleasant	600 mg/l

Reference

IS: 10500 – 1992 – Drinking water [SPECIFICATION]