Question raised in Lok Sabha on Pollution in Major Rivers, 16/03/2018. Rivers in the country are mainly polluted due to discharge of untreated and partially treated sewage from cities/towns and industrial effluents. Central Pollution Control Board (CPCB) has informed that there are a total number of 2892 Grossly Polluting Industries (GPIs) discharging effluent into water bodies, including rivers, across the country. These industries are required to meet the prescribed effluent quality norms before discharging their treated effluent into rivers & other water bodies.