In the Himalayan terrain, the Kosi river is formed by the confluence of seven smaller streams, viz. Indravati, Sun Kosi, Tama Kosi, Likhu Kosi, Dudh Kosi, Arun Kosi and Tamar Kosi at different places in China, Tibet and Nepal, before its entry into the Indian state of Bihar. The Kosi river is responsible for many floods in Bihar.

This paper describes the pollution status of fourteen major drains, namely Najafgarh drain, Magazine Road, Sweeper Colony, Khyber Pass, Metcalf House, Kudesia Bagh, Civil Mill, Sen Nursing Home, Drain No. 14, Barapulla, Maharani Bagh, Kalkaji, Okhla and Shahdara drain entering into the river Yamuna at Delhi, studied during the year 1999-2000.

A study to assess the supply of drinking water quality in Delhi, by examining the various physico-chemical parameters, namely pH, conductivity, TDS, SS, DO, BOD, COD, calcium and magnesium hardness, total hardness, alkalinity, salinity, turbidity of the pre-treated water samples from Bhagirathi, Wazirabad, Chandrawal, Haiderpur and Okhala Water Treatment Plants has been carried out.