The rapid urbanisation and industrialisation in the last few decades has led to water pollution. Realising the importance of clean water, the Government passed the Water Prevention and Control of Pollution Act in 1974 that made it mandatory to treat waste water in treatment plants. The treatment consists of three stages: primary, secondary and tertiary.
The waste water is treated in two stages. The first stage includes treatments like conventional sedimentation, filtration and chlorination while in the second stage, the wastewater is passed through six connected marshes, which contain an appropriate balance of plants, algae, fungi and bacteria. As wastewater passes through the series of marshes, all the living organisms in it neutralises, absorbes and assimilates the toxic pollutants such as heavy metals. Besides cleaning waste water, marshes develop into sanctuaries, thereby increasing the biodiversity of the region.
Around 150 litres of wastewater is generated by an individual daily, and a large amount of it is generated from toilets. A sustainable system for handling human excreta by using dry composting toilets is ecological sanitation or EcoSan. Such EcoSan toilets not only eliminate wastewater generation but also generate the natural fertiliser from recycled human excreta, which forms an excellent substitute for chemical fertilisers.