Context: The Central Groundwater Board (CGWB) reported that 20% of Delhi's groundwater samples exceed the permissible nitrate limit
- The Basics: * Sources: Primarily caused by excessive use of nitrogenous fertilizers (Urea), leaching from septic tanks, and industrial waste.
- Health Impact: High nitrates cause Methemoglobinemia (Blue Baby Syndrome) in infants. It reduces the ability of blood to carry oxygen.
- Latest Data (CGWB 2024 Report):
- National Trend: 440 districts in India now report excessive nitrate, up from 359 in 2017.
- Seasonal Variation: Contamination often increases after the monsoon due to surface runoff from agricultural fields washing fertilizers into aquifers.
- Subject Reference:
- GS Paper III: Environment (Pollution), Agriculture (Fertilizer subsidy and its impact).
- GS Paper II: Health and Governance (Drinking water schemes like Jal Jeevan Mission).
IAS-2026 - OPTIONAL / GEOGRAPHY / PUBLIC ADMINISTRATION / SOCIOLOGY / ANTHROPOLOGY / ORIENTATION ON 03 & 04-10-2025 
