Rainwater run-off from a rooftop is generally clean—as long as the catchment is kept clean. But there will always be some physical and minor organic contamination, which is why a simple sand filter is essential before storing the water in underground sumps or recharge structures.
In many apartment complexes, the challenge is space. Traditional filter chambers require area that builders often don’t have.
Here’s an example from Bangalore where we solved this constraint by using the setback space to install a semi-raised, multi-stage rainwater filter. This design efficiently handles run-off from a 1600 sq. m rooftop, enabling the community to harvest nearly 14 lakh litres of clean rainwater every year—without needing additional built-up space.
Smart design makes adoption practical. Sustainability is often about using what you already have, better.
