Nitrate in Drinking Water: Health Risks & WHO Safe Limits

Overview of Nitrate in Drinking Water

• What it is: Nitrate (NO₃) is a nitrogen-oxygen compound that occurs naturally at low levels but becomes a serious health concern when elevated. It's the most widespread groundwater contaminant globally.
• Why it matters: High nitrate is dangerous, especially for infants under 6 months—causing "blue baby syndrome" (methemoglobinemia) by reducing blood's oxygen-carrying capacity. It's also linked to certain cancers in long-term exposure studies.
• Natural sources: Small amounts occur naturally from soil nitrogen cycling. However, elevated levels almost always indicate human activity: agricultural fertilizers, animal waste, septic systems, and sewage are primary sources.
• Optimal range (0–10 mg/L): Pristine groundwater typically has less than 10 mg/L. This level indicates minimal agricultural or sewage impact. Safe for all consumers including pregnant women and infants.
• Too high (>50 mg/L): WHO limit is 50 mg/L (as nitrate). Water exceeding this is unsafe for drinking, especially for infants, pregnant women, and the elderly. Requires treatment or alternative source.
• Warning sign: Nitrate is a sentinel indicator—if elevated, other contaminants like pesticides and bacteria may also be present. Regular testing is essential in agricultural areas and homes with private wells.