Despite flaws, Namma Metro’s RWH has significant benefits

The rainwater harvesting (RWH) installation on the 6.7-km stretch between MG Road and Baiyyappanahalli (Reach 1) revealed its benefits despite infrastructural flaws.

It also highlighted the need to implement RWH across the metro network.

The Bangalore Metro Rail Corporation Limited’s (BMRCL) RWH system involves a pipe carrying storm water from the elevated viaducts into the pits between the pillars.

Eight volunteers who surveyed the RWH infrastructure of 156 pillars between the Reach 1 stations noticed an immediate need for repairs and upgrade.

They found pipes broken at eight pillars, 300-litre capacity water tanks clogged at four places, and trash covered over seven others.

The team further spotted broken caps at five places and lids missing on 14 water tanks.

While welcoming the effort to build the RWH infrastructure, the study flagged lack of maintenance as it suggested ways to reap the full benefit of the system.

Among the suggestions were a steel mesh to prevent trash clogging the pit, besides clearing existing trash. It also suggested that the leaking pipes be fixed.

“Rainwater harvesting needs maintenance on regular basis, particularly at least a month before the monsoon. Regular monitoring of pipes, pits and water tanks is needed so that RWH structures are functional,” it said.

An official DH reached out to acknowledged the problems and assured they will take remedial steps.

“In Phase 1, the RWH system on Reach 2 (Mysuru Road), 3 (Nagasandra) and 4 (Yelachenahalli) is non-existent due to implementation challenges. In several places, pits were not dug as hard rock was found at the site,” an official explained.

Another official, who saw the work from close quarters, admitted that the RWH system on Reach 1 was built professionally.

“Seriousness (regarding RWH implementation) was lost in other stretches. We came under pressure due to delay in the Phase 1 work, especially the underground network. The results are there to see,” he said, observing that roads in Reach 1 fair better during monsoon.

‘BMRCL must introduce an RWH audit'

Raghavendra B Pachhapur of ActionAid said Bengaluru will soon have 100 kilometres of metro viaduct network, which will help the city’s water security.

“Bengaluru, at 920 metres above sea level, is losing rainwater. On the other hand, we are (rapidly) drawing groundwater. Bengaluru’s thirst is not quenched by Cauvery even after the 4th phase of the pipeline. Added to it, we are in a mad rush for concretisation across the city leaving less or no space for rainwater percolation,” Raghavendra said.

Raghavendra urged the BMRCL to introduce an RWH audit and provide regular information about water harvested by its infrastructure.