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File photo of a devotee carrying Lord Ganesha idol on his head during Ganesh immersion in Mumbai.
| Photo Credit: Emmanual Yogini
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Ganesh Chaturthi is one of India’s most celebrated festivals, and every year, the deity’s idols weighing many tonnes are immersed in the country’s water bodies, polluting the water.
Despite official regulations and recommendations, pollution caused by idol immersion has been difficult to curb.
Plaster of Paris has become the dominant building material for these idols over the years. It is non-biodegradable. Dyes and paints used to colour these idols have also been known to contain mercury, zinc, cadmium, and lead in harmful quantities. Most idols also use plastics and thermocol for decoration, both materials that don’t degrade for a long time.
Considering it’s also hard enough for use in construction and as a bone graft substitute, plaster of Paris ensures the idols remain in the water for months or even years, depending on their size. And when they do dissolve, they increase the local concentration of calcium ions, which increase the water’s hardness, and sulphate ions, which are known to be harmful in large quantities to animals, humans, and plants.
When dissolved in water, lead can find its way into sediments and aquatic food chains, eventually increasing the risk of neurological damage and cardiovascular risk in humans. It can also cause developmental delays in infants. Likewise, prolonged exposure to cadmium can cause kidney disorders and enfeeble the heart.
Mercury is notorious for its ability to damage the neurological and reproductive systems and to impair cognition. Hexavalent chromium compounds are a known human carcinogen.
According to the Bureau of Indian Standards, the acceptable limit for lead, cadmium, mercury, and total chromium in drinking water is 0.01, 0.003, 0.001, and 0.05 mg/L respectively, with no relaxations allowed. The acceptable pH value of drinking water needs to be between 6.5-8.5.
A case study, conducted in Bengaluru by the Central Pollution Control Board to measure the impact of Ganesh idol immersion in lakes, found increased acid content in the water. The study also found elevated levels of heavy metal in the water bodies after idol immersion – iron increased nearly 10 times, while copper in sediments increased by 200-300%.
Other than harming health, toxic compounds in water bodies can also add to the sedimentation and bioaccumulation in aquatic organisms, and disrupt the chemistry and natural pH of water bodies.
Religious gatherings add a complex layer to environmental pollution in India. Phool, a business initiative that upcycles organic waste from Indian temples, estimates that more than eight million tonnes of flowers are discarded in rivers in South Asia annually during religious activities. Other practices, like lighting incense and earthen lamps contribute to air pollution, and using loudspeakers increases noise pollution. Even though the core principles of most religions advocate living in harmony with the environment, commercialisation of festivals and religious practices has increased the waste generation and environmental degradation they cause.
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Published – September 03, 2025 01:48 pm IST
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