Varanasi, a city of one million people that many pilgrims visit to take a "holy dip" in the Ganges, releases around 200 million litres of untreated human sewage into the river each day, leading to large concentrations of faecal coliform bacteria.
According to official standards, water safe for bathing should not contain more than 500 faecal coliforms per 100ml, yet upstream of Varanasi's ghats the river water already contains 120 times as much, 60,000 faecal coliform bacteria per 100 ml.