Why this matters now
Water pollution and conservation feature in GS-3 and current affairs (river cleaning, groundwater stress). The indicators (BOD/COD/DO) and Namami Gange are common points.
Sources of water pollution
Major sources include untreated sewage, industrial effluents, agricultural run-off (fertilisers and pesticides), and solid waste. Nutrient run-off causes eutrophication — algal blooms that deplete oxygen and kill aquatic life. Groundwater can be contaminated by arsenic, fluoride and nitrates.
Indicators of water quality
- BOD (Biochemical Oxygen Demand) — oxygen needed by microbes to break down organic matter; high BOD = more pollution;
- COD (Chemical Oxygen Demand) — oxygen needed to oxidise all matter (organic + chemical);
- DO (Dissolved Oxygen) — oxygen available to aquatic life; low DO = poor water quality.
Laws and programmes
The Water (Prevention and Control of Pollution) Act, 1974 (with the CPCB/SPCBs) is the key law. Major programmes include Namami Gange (the flagship mission to clean and rejuvenate the Ganga), the National River Conservation Plan, and sewage-treatment infrastructure.
Water conservation
With growing water stress, conservation is vital — rainwater harvesting, watershed management, micro-irrigation (drip/sprinkler), reuse of treated water, and demand management. Initiatives like the Jal Shakti Abhiyan and Atal Bhujal Yojana promote water security.
UPSC angle
Know the sources, eutrophication, the quality indicators (high BOD = polluted; low DO = poor), the Water Act 1974, and Namami Gange. Conservation: rainwater harvesting, watershed & micro-irrigation.
Frequently asked questions
What is eutrophication?
Nutrient enrichment of water (from fertiliser/sewage run-off) that causes algal blooms, depletes dissolved oxygen and harms aquatic life.
What do BOD, COD and DO indicate?
BOD and COD measure pollution load (oxygen demand); DO is the dissolved oxygen available to aquatic life — low DO means poor water quality.
Which law controls water pollution in India?
The Water (Prevention and Control of Pollution) Act, 1974, implemented through the CPCB and State Pollution Control Boards.
What is Namami Gange?
The flagship mission to clean, conserve and rejuvenate the river Ganga.