During the annual five day Durga Puja festival, Hindus spend five days paying worship to statues of the goddess Durga and her children. Then, as the festival ends, the statues are immersed in the nearest body of water.
In religious terms, this ritual represents Durga's return to her husband, Shiva, at their home in the Himalayas, and celebrates her defeat of the evil god. In terms of urban governance, though, the hundreds of thousands of statues dumped every year represents a huge source of pollution throughout the nation's waterways and lakes.
The problem stems from the materials used in the idols' construction. In most cases, this is still plaster of Paris, metal, and various chemical-based paints; all of which disintegrate in the water and pollute it.
Hindu communities in other countries like Burma and Bangladesh also immerse statues during festivals, but India's majority Hindu population, and the popularity of the Durga Puja fesitval in states like Assam and Odisha, means the build-up of statues and the pollutants they create is particularly bad there.
Various studies have been conducted in India recent years to figure out the extent of the problem. Scientists in Hyderabad discovered highl levels of zinc, calcium and strontium in water samples from a lake containing hundreds of Ganesh and Durga statues. A study of a lake in Bhopal, India found that idol immersion is a "major source of contamination and sedimentation to the lake water". This isn't good for nearby plants and animals, or anyone who uses the lake or river as a source of drinking water.
A Durga statue floats on the river in Siliguri, West Bengal. Image: Getty.
Contamination researchers and local and central governments are trying to encourage worshippers to use statues made of a softer clay, which would dissolve quickly and sink to the river or lake floor, and natural food colourings rather than chemical-based paint. Local authorities are also increasingly arranging large clean-up operations in the wake of festivals.
Another solution is to create special, synthetically lined pools for idol immersion. In Hyderabad, for example, the chief minister is pushing for a dedicated statue-immersion pool to be constructed near the highly polluted Hussainsagar Lake.
Either way, idol pollution still pales in comparison to the other types of refuse pouring into the country's lakes and rivers: 80 per cent of the nation's sewage, plus agricultural runoff and waste from unregulated small industry. We can't blame the gods for everything.