Criteria for drinking water quality recommended by WHO includes – a) Colour < 15 TCUb) pH 6.5–8.5c) Chloride 200–600 mg/1d) Turbidity <5 NTUe) Zinc < 4 mg/1

Guidelines of for drinking water Colour < 15 true colour units (TCU) Turbidity < 1 nephlometric turbidity units (NTU) (has been changed in 22nd /e of Park) Hardness < 100 — 300 mg/litre calcium ion pH: 6.5 — 8.5 Total dissolved solids (TDS) < 600 mg/litre Chloride    200 - 600 mg/L  H2S < 0.05 mg/L Iron < 0.3 mg/L Sodium < 200 mg/L Sulphate < 250 mg/L Zinc < 4 nag/L NH3 < 1.50 mg/L Fluorine < 1.5 ppm (0.5 — 0.8 ppm: Optimum level) Nitrates < 50 mg/litre Nitrites < 3 mg/litre Gross alpha radiological activity < 0.1 Bq/litre Gross beta radiological activity < 1.0 Bq/litre Zero pathogenic microorganisms Zero infectious viruses Absence of pathogenic protozoa and infective stages of helminthes Dissolved O2 has indirect effect, level is not specified.