Sewage and Faecal Sludge: Where Does It Go?

How much of India's sewage is treated, why rivers remain polluted, and how faecal sludge from septic tanks can be managed safely.

Toilets solve one problem, but what happens to the waste that flows from them?

Sewage treatment gap

A 2021 report by the Central Pollution Control Board estimated that Indian cities generate about 72,000 million litres of sewage per day, while installed treatment capacity was less than half of that, and actual treatment was lower still, around 28 percent of sewage generated.

Untreated sewage flows into rivers, lakes and the sea.

River pollution

Rivers like the Ganga and Yamuna receive huge amounts of sewage. The Namami Gange programme, launched in 2014, funds sewage treatment plants and river cleaning.

Septic tanks and pits

Many Indian homes, especially in smaller towns and villages, use septic tanks or pits, not sewers. Their contents, called faecal sludge, must be emptied and treated.

Faecal sludge management

Desludging trucks empty tanks.
Sludge should go to treatment plants, not be dumped in fields or drains.
Some cities, like Warangal and towns in Odisha, developed faecal sludge treatment systems.

Costs and challenges

Sewer networks are expensive to build.
STPs often run below capacity or break down.
Operation and maintenance funding is weak.

Why it matters

Untreated sewage spreads disease, pollutes drinking water and harms ecosystems. Health gains from toilets depend on safe management of the waste.

The desludging truck

A town sets up a faecal sludge treatment plant. Private desludging operators must bring sludge there instead of dumping it in fields, and treated sludge is turned into compost for farmers.

Thinking building toilets solves sanitation

Sewage and sludge must be treated, or they pollute rivers and water.

Key takeaways

Indian cities generate about 72,000 million litres of sewage a day.
Only around 28 percent was treated, according to a 2021 CPCB report.
Many homes use septic tanks, requiring faecal sludge management.
Namami Gange and local systems aim to treat more sewage.