Sewage treatment gap
Topic: Geographical Issues: Pollution, Urban Waste, Slums and Land Degradation · NCERT: Beyond NCERT
Meaning
The sewage treatment gap is the difference between the sewage a city produces and the sewage it actually cleans. Sewage is the dirty water from homes, toilets and drains. When treatment plants are too few or work poorly, the untreated sewage flows straight into rivers, lakes and the sea. This gap is the main reason why most Indian rivers stay polluted even after cleaning programmes.
Example
Central Pollution Control Board data for 2020-21 showed Indian cities producing about 72,000 MLD (million litres a day) of sewage. Only about 28% of it was treated (verify current). Towns along the Ganga, such as Kanpur, Prayagraj, Varanasi, Patna and Kolkata, release domestic sewage that keeps faecal coliform (bacteria from human waste) high in the river.
Don't confuse with
- Sewage treatment capacity: this is how much sewage the plants are built to handle. The gap is about what is actually treated, which can be lower when plants run below capacity.
Related concepts
- Water pollution
- Water-borne diseases
- Biochemical oxygen demand
- Polluted river stretches
- Water (Prevention and Control of Pollution) Act 1974