Environment and Disaster Management › Pollution

Water pollution and river rejuvenation

The quality of India's rivers and drinking water: polluted stretches, sewage treatment, contaminants such as fluoride and arsenic, and the programmes that clean rivers. Prelims has asked what biological oxygen demand measures and which pollutants are found in drinking water in parts of India.

Foundation note: How a river is judged polluted: the classes, the standards and the sewage gap

Nothing here changed from 1 to 31 July 2026.Show all

biochemical oxygen demand: The oxygen microbes need to break down the organic matter in a sample of water, and so a measure of how much sewage the water carries.

environmental flow: The minimum flow a river needs to keep its ecosystem alive, notified stretch by stretch.

fit-for-purpose reuse: Treating wastewater only to the quality its intended use needs, such as irrigation or industrial cooling, rather than to drinking water standards.

flood line: The edge of the land a river inundates in a flood of a given size, used to set how far back building may come.

hexavalent chromium: The chromium (VI) form of the metal: soluble in water, bright yellow-green in it, toxic and carcinogenic, unlike the chromium (III) form.

Urban River Management Plan: A city plan that puts river health at the centre of urban planning.

Also filed elsewhere

Fluorosis · on Non communicable diseases, nutrition and food safety
Fluorosis is the harm done to the teeth and the bone by years of drinking groundwater that carries fluoride.