Inorganic water pollution in Nepal

Inorganic water pollution is contamination of water by non-biodegradable mineral and chemical substances such as arsenic, iron, manganese, nitrate, ammonia, fluoride, hardness salts, heavy metals (lead, chromium, cadmium, mercury) and suspended sediment. These do not decompose and can harm health even at low concentration over long periods.

Severity of the problem in Nepal

1. Arsenic in Terai groundwater – shallow tube wells in districts such as Nawalparasi, Rautahat, Bara, Parsa, Kailali and Bardiya contain arsenic above the national standard (50 µg/L, NDWQS 2062) and far above the WHO guideline (10 µg/L). Long-term drinking causes arsenicosis: skin lesions, keratosis, and cancers of skin, lung and bladder. Hundreds of thousands of people have been estimated to be at risk.
2. Iron and manganese – very common in Terai and Kathmandu valley groundwater; cause reddish colour, bad taste, staining of clothes and utensils, and growth of iron bacteria in pipes.
3. Ammonia and nitrate – Kathmandu valley deep groundwater has high ammonia; shallow wells near septic tanks and farms show nitrate, which can cause methaemoglobinaemia (blue-baby syndrome) in infants.
4. Heavy metals from industries – tanneries (chromium), dyeing, battery and metal works discharge effluent without treatment into rivers such as the Bagmati and in industrial corridors like Biratnagar–Itahari and Birgunj–Pathlaiya.
5. Agro-chemicals – increasing use of fertilisers and pesticides; residues reach streams and shallow wells.
6. Sediment – high turbidity in monsoon rivers from landslides and erosion makes treatment costly and damages hydropower turbines.
7. Hardness – high calcium and magnesium in some hill and Terai sources.
8. Weak monitoring – many small rural and private sources are never tested; people do not know their water is unsafe because many inorganic pollutants have no colour, taste or smell.

Plans to mitigate

1. Testing and mapping – test all tube wells for arsenic, iron and nitrate; mark unsafe wells (red) and safe wells (green); publish a water-quality map.
2. Alternative safe sources – deep tube wells below arsenic layers, piped supply from rivers or springs, rainwater harvesting.
3. Household treatment – arsenic biosand filter / Kanchan filter, iron removal filters, aeration and sedimentation.
4. Community treatment plants – aeration, coagulation, filtration and adsorption plants for iron, manganese and arsenic in towns.
5. Industrial pollution control – enforce effluent standards; require effluent treatment plants; relocate polluting industries to industrial estates with combined treatment; "polluter pays".
6. Safe agriculture – integrated pest management, organic farming, controlled fertiliser use.
7. Sanitation siting – keep septic tanks and pits away from wells to cut nitrate and ammonia.
8. Watershed and river protection – afforestation, river-bank protection, ban on dumping waste in rivers.
9. Health measures – screening and treatment of arsenicosis patients; nutrition support.
10. Awareness – educate users through FCHVs, schools and local bodies.
11. Law and institutions – enforce the National Drinking Water Quality Standards 2062 and the Water Resources Act; strengthen labs at local and provincial level.