The Karnataka State Pollution Control Board (KSPCB) is now mandating the use of treated water from sewage treatment plants (STPs) for construction activities in the city. This initiative aims to reduce the pressure on Bengaluru's precious groundwater resources, estimated to be worth an INR 3,584 crore (USD 48 billion). The city's booming construction industry, particularly large tech parks, consumes a significant amount of water. By leveraging treated water, Bengaluru can significantly reduce its dependence on groundwater and ensure long-term water security for its residents.

While the move promotes water conservation, some builders expressed concerns about the quality of treated water and its impact on the strength of concrete structures, a multi-billion-dollar industry in India. Scientists from the Indian Institute of Science (IISc) addressed these concerns, assuring the construction industry of the safety and effectiveness of treated water for construction.

Professor LN Rao, from the Centre for Sustainable Technologies at IISc, highlighted a comprehensive study that confirmed the suitability of treated water. The study monitored the quality of treated water over a period of time, observing no adverse effects on concrete strength. Researchers emphasized the importance of using treated water only for mixing cement and curing structures, not for personal purposes, potentially saving construction companies money on overall water usage.

The success of this initiative hinges on collaboration between various stakeholders. Sewage treatment plants (STPs) must strictly adhere to water quality parameters set by regulatory bodies. A 2021 report by the Central Pollution Control Board (CPCB) revealed that only 30% of STPs in India meet the required standards. Upgrading these facilities and ensuring proper maintenance will be crucial for providing builders with consistent access to high-quality treated water.

Apartment complexes can also play a role by implementing systems to separate black water (toilet waste) and greywater (kitchen and bathroom wastewater). This reduces the energy needed to treat the water at STPs, lowering operational costs and environmental impact. Additionally, exploring rainwater harvesting can further lessen the reliance on groundwater and treated water for non-essential construction activities like dust suppression.

The use of treated water for construction presents a win-win situation for Bengaluru. It conserves valuable groundwater resources and provides a solution for apartment complexes struggling to dispose of excess treated water. In March, the Bangalore Water Supply and Sewerage Board (BWSSB) authorized residential communities to sell a portion of their treated water commercially, excluding use in food and medicine production. This program has the potential to generate additional revenue streams for apartment complexes, offsetting some operational costs.

A pilot program is currently underway, with 15 apartments in Bellandur supplying treated water to construction sites within a 5-kilometer radius. The success of this pilot is expected to pave the way for a city-wide expansion of the program. Industry experts estimate that widespread adoption of treated water could save Bengaluru up to 15% of its construction water consumption, translating to millions of litres saved annually.

By embracing treated water for construction, Bengaluru is taking a significant step towards a more sustainable future. This initiative not only addresses water scarcity concerns but also paves the way for innovative practices in the construction industry. As the program expands and awareness grows, treated water is poised to become a mainstream choice for building a greener Bengaluru.

Furthermore, this initiative can serve as a model for other water-stressed cities in India and around the world. By promoting collaboration, innovation, and responsible water management practices, Bengaluru is charting a course for a more sustainable future where water security goes hand-in-hand with economic development.