From Wikipedia:
Along the 4 miles (6.4 kilometres) stretch of terraced bathing ghats in the holy city of Varanasi, the water of the Ganges is a "brown soup of excrement and industrial effluents."[10] The water there contains 60,000 faecal coliform bacteria per 100 ml, 120 times the official limit of 500 faecal coliforms/100ml that is not considered safe for bathing.[10]