The civic body is thinking of allowing builders to use sewage water for construction.
This can save over 15 per cent of daily supply of potable water currently being used for construction activities that have increased in the city. The Brihanmumbai Municipal Corporation (BMC) will chalk out guidelines, which builders will have to follow strictly.
Sewage water contains traces of metals, chlorides, solid substance that can hamper the quality of construction.
Guidelines will include scientific processing of the water to reduce the level of toxicity. The amount of water that can be used and the nature of constructions will be considered while forming guidelines.
“Builders will have to do the processing in accordance with our specifications. They will have to give us the water’s toxicity in writing. We shouldn’t be held responsible if a building collapses,” said a civic official requesting anonymity.
“We can sell sewage water for construction purposes at the rate of Rs 2.7 per 1,000 litres. But the discharge will need to soften, as the level of toxicity is high and it can’t be used directly,” he added.
The city generates 2,600 million litres of sewage every day, which is treated at seven units to match the environmental norms before being let out in the sea.
The builders will have to make arrangements of transporting the water to the site. “We have advised them a technique called direct serial drilling. With this they can directly draw water from our sewer mains, or they can take discharge from our units,” said the official.
Deputy Municipal Commissioner (Sewerage Operations) D.L. Shinde said: “Builders will have to submit a comprehensive plan about the kind of processing the discharge will need.”