Water pollution refers to the contamination of water bodies (such as rivers, lakes, oceans, and groundwater etc.) by harmful substances or pathogens, making them unfit for human use or harmful to aquatic life. Water pollution comes from two sources: point or non-point sources. Point sources refer to a single identifiable source for the pollution, whereas non-point sources mean that the pollution comes from a variety of sources that are non-identifiable. There are numerous point and non-point sources, including industrial discharge, agricultural runoff, untreated sewage, and improper disposal of waste. The presence of pollutants in water can have serious environmental, health, and economic consequences.

Water pollution is a major environmental issue in India. India only holds about 4% of freshwater resources, yet nearly 70% of surface water in India is unfit for consumption. 163 million Indians lack access to safe drinking water and about 21% of communicable diseases are linked to poor quality water. The largest source of water pollution in India is untreated sewage. Other sources of pollution include agricultural runoff and unregulated small-scale industry. Most rivers, lakes and surface water in India are polluted due to industries, untreated sewage and solid wastes. Although the average annual precipitation in India is about 4000 billion cubic metres, only about 1122 billion cubic metres of water resources are available for utilization due to lack of infrastructure. Much of this water is unsafe, because pollution degrades water quality. Water pollution severely limits the amount of water available to Indian consumers, its industry and its agriculture.

India is one of the most water stressed countries in the world, with only 4% of freshwater resources. Water resources continue to dwindle, and while climate change is exacerbating this, there are issues of water pollution, which the following sections will tackle. In India, there are two main types of water resources: surface water and groundwater.

Surface water refers to the water in rivers, lakes, wetlands, and reservoirs. The main surface water bodies in India is the Ganges, Brahmaputra and the Barak, which account for 60% of the surface water in India. India divides its surface water into 22 basins. The Ganges is the longest river in India, flowing across 11 states, but India additionally has a variety of lakes, with nearly 1,000 large and medium-sized lakes. Groundwater refers to the water under the surface, stored in aquifers. This accounts for nearly 40% of usable water in India. Groundwater in India is classified into 14 system and these are subdivided into 42 major aquifers.

More than 500 million people live along the [Ganges] River. An estimated 2,000,000 persons ritually bath daily in the river, which is considered holy by Hindus. Ganges river pollution is a major health risk.

NRGBA was established by the Central Government of India, on 20 February 2009 under Section 3(3) of the Environment Protection Act, 1986. It also declared Ganges as the "National River" of India. The chair includes the Prime Minister of India and Chief ministers of states through which the Ganges flows.

By an estimate by 2012, Delhi's sacred Yamuna river contained 7,500 coliform bacteria per 100cc of water. A number of NGOs, pressure groups, eco-clubs, as well as citizens' movements, have been active in their task to clean the river.

Even though India revised its National Water Policy in 2002 to encourage community participation and decentralize water management, the country's complex bureaucracy ensures that it remains a "mere statement of intent." Responsibility for managing water issues is fragmented among a dozen different ministries and departments without any coordination. The government bureaucracy and state-run project department has failed to solve the problem, despite having spent many years and $140 million on this project.