The Bureau of Indian Standards (BIS) acceptable limit for nitrate in drinking water (IS:10500) and the WHO guideline value are respectively:

• A 45 mg/L and 10 mg/L (as NO₃⁻)
• B 50 mg/L and 50 mg/L (as NO₃⁻)
• C 45 mg/L and 50 mg/L (as NO₃⁻) ✓
• D 10 mg/L and 45 mg/L (as NO₃⁻)

Explanation

The BIS standard (IS:10500) for nitrate in drinking water is 45 mg/L (as NO₃), corresponding to 10 mg/L as NO₃-N; the WHO guideline value is 50 mg/L (as NO₃). Excess nitrate causes methemoglobinemia (blue baby syndrome) in infants under 6 months. Agricultural run-off and improper sewage disposal are the main sources of nitrate contamination in groundwater.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.