Urban Waters - Bengaluru Rainwater Water Harvesting

Bengaluru’s rainfall

Bengaluru’s growth has far outpaced water-infrastructure development. Along with the increased population comes a change in the land use patterns. What was earlier primarily agricultural land now houses concrete buildings and roads. The overall result is lesser percolation of rainwater into the ground and aquifers.

A simple analysis comparing actual costs for these various sources of water considering both capital and maintenance costs reveals that rainwater is actually the cheapest source of water and tanker water that is brought in from remote locations the most expensive at about Rs 60/- per KL. The costs for BWSSB supplied water is in the range of Rs 30/- to Rs 40/- per KL accounting for the various leakages and losses in the system. The BWSSB manages its costs for water by levying an increasing block tariff of water. Ground water from shallow and deep wells is slightly more economical at Rs 6/- and Rs 16/- per KL respectively.

It is also interesting to note that while the affluent and middle class is able to get water at about 6 paise per liter (from either BWSSB, tankers or groundwater), the poor often end up paying about Rs 8/- per bucket of water which work out to about 20 paise per liter.

Rooftop rainwater harvesting was made mandatory as per building bye-laws in 2005. Through the amendment of the BWSSB Act, in 2009, BWSSB has also made it mandatory for all urban land-use above 2400sq ft to implement Rainwater harvesting. It has also laid down the technical guidelines for the same – the water harvesting has to be designed for a 20mm rainfall event. However, rainwater harvesting solutions have not been fully embraced by the citizens.