Water is typically referred to as polluted when it is impaired by anthropogenic contaminants and either does not support a human use, such as drinking water, and/or undergoes a marked shift in its ability to support its constituent biotic communities, such as fish. Natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes in water quality and the ecological status of water.
Water pollution is a major global problem which requires ongoing evaluation and revision of water resource policy at all levels (international down to individual aquifers and wells). It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily. An estimated 700 million Indians have no access to a proper toilet, and 1,000 Indian children die of diarrheal sickness every day. Some 90% of Chinas cities suffer from some degree of water pollution, and nearly 500 million people lack access to safe drinking water. In addition to the acute problems of water pollution in developing countries, developed countries continue to struggle with pollution problems as well. In the most recent national report on water quality in the United States, 45 percent of assessed stream miles, 47 percent of assessed lake acres, and 32 percent of assessed bays and estuarine square miles were classified as polluted.
The Ganges is a the largest river in India with an extraordinary religious importance for Hindus. Along its banks are some of the worlds oldest continuously inhabited places like Varanasi, Patna. It provides water to about 40% of Indias population in 11 states. In the modern times, it is known for being very polluted . In Varanasi alone, an estimated 2.9 billion liters or more of untreated human sewage is discharged into the Ganges daily, although the existing infrastructure has a capacity to treat only 1.1 billion liters per day, leaving a huge deficit.
Human waste The Ganges river basin is one of the most fertile and densely populated in the world and covers an area of 400,000 sq miles (1,000,000 sq km). The river flows through 29 cities with population over 100,000, 23 cities with population between 50,000 and 100,000, and about 48 towns . A sizable proportion of the effluents in Ganges are caused by this population through domestic usage like bathing, laundry and public defecation.
Dams Built in 1854 during the British colonization of India, the Haridwar dam has led to decay of the Ganges by greatly diminishing the flow of the river. The Farakka Barrage was built originally to divert fresh water into the Bhagirathi River but has since caused an increase of salinity in the Ganges, having a damaging effect on the ground water and soil along the river . Apart from this, Bangladesh and India faced major tensions due to this barrage. The government of India planned about 300 dams on the Ganges in the near future and the tributaries despite a government-commissioned green panel report that has recommended scrapping 34 of the dams citing environmental concerns. .
Industrial waste Countless tanneries, chemical plants, textile mills, distilleries, slaughterhouses, hospitals contribute to the pollution of the Ganges by letting untreated wastes into it. Industrial effluents are about 12% of the total volume of effluents reaching the Ganges. Although a relatively low proportion, they are a cause for major concern because they are toxic and non-biodegradable.
Ganga Action Plan The Ganga Action Plan or GAP was a program launched by Rajiv Gandhi in April 1985 in order to reduce the pollution load on the river. The program was launched with much fanfare, but it failed to decrease the pollution level in the river, after spending 901.71 Crore (~190 million USD adjusting to inflation) . The activities of GAP phase I initiated in 1985 were declared closed on 31 March 2000. The steering Committee of the national river conservation Authority reviewed the progress of the GAP and necessary correction on the basis of lessons learned and experiences gained from the GAP phase; 2.00 schemes have been completed under this plan. A million liters of sewage is targeted to be intercepted, diverted and treated. The Phase-II of the program was approved in stages from 1993 onwards, and included the following tributaries of the Ganges: Yamuna, Gomti, Damodar and Mahananda. As of 2011, it is currently under implementation.
National River Ganga Basin Authority (NRGBA) 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 .
Cities with sanitary sewer overflows or combined sewer overflows employ one or more engineering approaches to reduce discharges of untreated sewage, including: utilizing green infrastructure approach to improve stormwater management capacity throughout the system, and reduce the hydraulic overloading of the treatment plant repair and replacement of leaking and malfunctioning equipment increasing overall hydraulic capacity of the sewage collection system (often a very expensive option).