Bengaluru’s 34 government-run sewage treatment plants (STPs) together process 1,350 million litres of wastewater daily, yet the output remains unsuitable even for non-potable purposes such as flushing toilets, cleaning streets, or watering gardens.
In the state assembly, Shivajinagar MLA Rizwan Arshad questioned why. The Bangalore Water Supply and Sewerage Board (BWSSB) admitted that the city’s STPs perform only primary and secondary treatment — removing solids and using microbes to break down organic matter. For safe reuse, water requires tertiary treatment, an advanced process that eliminates odour, improves clarity, and removes chemical and bacterial contaminants.
The hurdle is cost: at roughly ₹2 crore per million litres per day, upgrading the entire system would demand ₹2,700 crore. With BWSSB strapped for funds and the government prioritising welfare schemes, the project is not on the horizon. For now, treated water is released into lakes in Kolar, Chikkaballapur, and Bengaluru Rural districts under the Koramangala–Challaghatta Valley Project.
Arshad argued that reusing treated water is essential for Bengaluru’s water-stressed future, urging investment in modern technologies. Interestingly, several private apartment and commercial STPs already produce near-potable water, though limited by lack of dual plumbing and conservative user habits. Much of this water is diverted for construction and industrial use.
Deputy CM D K Shivakumar said upgrades could be considered if industrial demand rises and BWSSB’s finances improve. In contrast, Singapore’s NEWater initiative shows what’s possible — recycling sewage into high-quality drinking water through microfiltration, reverse osmosis, and UV disinfection, meeting 40% of the city-state’s needs.