"We talk a lot about industrial pollution of our rivers, but sewage pollution is a big problem," Sunita Narain, director of the Centre for Science and Environment, told reporters.

"What is happening to the Yamuna is reflective of what is happening in almost every river in India," she added. "The Yamuna is dead, we just haven't officially cremated it yet."

According to the Central Pollution Control Board, around 70 percent of the pollution in the Yamuna is human excrement.

This results in water-borne diseases such as diarrhoea -- one of the biggest killers of children in India -- and affects thousands of poor people living near the river who drink the water and bathe in it.

Environmentalists say while India has over 300 sewage treatment plants, most are underutilised and poorly positioned. Treated waste is often mixed with untreated sewage and thrown back into rivers.

India's drainage system is also decrepit and in serious need of repair, with more than half of the country's drains virtually redundant.

Narain said India's sewage management and treatment system needed to be revamped and rivers kept clean, rapid industrialisation and urbanisation leading to greater demand for water.

Climate change is also another threat to India's water supplies with Himalayan glaciers -- the source of many of India's rivers -- rapidly receding, and erratic rainfall predicted due to global warming.

Skirmishes are beginning to occur in parts of India where farmers have been protesting over rights to more water, Narain added.