With the severe water scarcity in Bengaluru, a large number of residents have to buy water, more so during summers. And due to indiscriminate digging of borewells in the rush to find water, the city’s groundwater has been overexploited.
But the efforts of many Bengalureans in rainwater harvesting (RWH) already show the way ahead for the city. Currently, Bengaluru is the Indian city with the second-highest number of RWH installations (1.55 lakh), next only to Chennai. Highlighting such efforts, and discussing how to amplify these, was the focus of a webinar jointly organised by BWSSB (Bengaluru Water Supply and Sewerage Board), Biome Environmental Solutions, and Citizen Matters on July 10th.
Speaking at the event, G Asok Kumar, Additional Secretary at Centre’s Jal Shakti Ministry, discussed the ministry’s ‘Catch the Rain’ campaign to promote RWH across the country. He said the idea is to nudge stakeholders to build suitable RWH structures with public participation, before the onset of the monsoon. (Bengaluru typically gets much of its rainfall between August to October, and hence the time is now right for install RWH structures.)
In addition to replenishing groundwater and meeting a portion of the city’s water demand, RWH can also mitigate urban floods. “With climate change, there are more intense rainfalls. But urbanisation and concretisation reduces the permeability of soil and water does not go down (recharge) properly. This has led to floods in many Indian cities in the last few years,” Asok Kumar said.
As part of the campaign, Asok Kumar said the plan for Bengaluru is to have “rooftop RWH structures, enumeration of all water bodies and preventing their encroachment, protecting them with public participation, and reviving traditional RWH structures like wells.”
K N Rajeev, Additional Chief Engineer at BWSSB, explained that since Cauvery water is pumped almost 100 km away from the city, the production cost is quite high at Rs 41 per kilolitre. And hence the rainwater available freely in the city needs to be utilised.
Water-starved communities have led the way in rainwater harvesting
At the webinar, Rakshitha M L, Programme Officer at Biome, discussed different RWH options. She explained how rainwater filtered and collected in rain barrels or sumps can be used directly for drinking and other purposes. And how excess water could be channeled to recharge wells to enhance groundwater levels.
Further, the owners of apartments and individual houses shared their success stories. At Nandi Deepa apartment in Hulimavu, the owners’ association had set up an RWH system to channelise rainwater falling on the rooftops of all six blocks in the complex. The water is stored in sumps for direct use, and the excess is channeled to four percolation pits as well as the community’s open well, resulting in groundwater recharge.
Since 2015, the community had spent around Rs 15 lakh annually for buying tanker water. After RWH installation this cost has reduced drastically, even though the initial investment for RWH was massive, says Prasanna, a resident here: “We spent Rs 17-18 lakh for the RWH system. This included rejuvenating our community well, cleaning our drains and percolation pits, etc. We also spent around Rs 10 lakh for removing old PVC drums and building three RCC sumps that can together hold 60,000 litres of water. But with this, the money we spent for tanker water annually has reduced from Rs 15 lakh to Rs 3 lakh straight – that is, savings of 80%!”
The community is now building another percolation pit to ensure that no rainwater goes outside the compound. The quality of the rainwater collected in the community well was found to be higher than that of borewell and tanker water. But since the water had some turbidity (cloudiness), it’s being treated and then supplied to residents. Along with this, the apartment uses water from their Sewage Treatment Plant (STP) for flushing toilets and cleaning floors, which further reduces the demand for tanker water.
Joe, another resident explained how the community was convinced to implement RWH: “We formed a separate task force for water, where we brought in like-minded people who could give innovative ideas, so that there would be no disputes later.”
At Aditi Elite apartment in Bellandur, the RWH system was set up such that rainwater is filled in sumps for reuse and the excess is channeled into four pre-existing borewells. The cost for setting up the system was only Rs 2.5 lakh, said resident Ashok Mruthyunjaya. “Acute water shortage was the basic motivation that drove this – any apartment in Bellandur has to spend lakhs of rupees to buy water. We convinced residents with a lot of data points,” said Ashok.
Livelihood for traditional well-diggers, plumbers
The webinar also featured traditional well-diggers from the Bhovi community who are now involved with building RWH structures. Bhovi community had been forgotten in Bengaluru as the digging of open wells nearly stopped in the last 15 years. Now, digging of recharge wells is becoming a source of livelihood for them. The community, concentrated in villages (often called Bovipalya or Vaddarpalya) of rural Bengaluru, uses its traditional skills and understanding of soil textures and water availability, etc., to build recharge wells.
Raghupati, a well-digger said, “My parents, grandfather have all done this work, and I learned it from them. RWH-related work started recently; now I do RWH work, cleaning old wells and digging new wells, etc.” Citing the example of a layout where RWH led to borewells yielding water, he said, “I enjoy this work and would like to continue it.”
Enforcement ongoing, will consider incentives too: BWSSB
BWSSB officials pointed out that they have been promoting RWH through their RWH theme park in Jayanagar, which demonstrates 27 working models. The theme park was set up as a one-stop solution to create awareness amongst citizens, and to train architects, engineers, plumbers, etc. It used to get around 50,000 visitors per month before COVID. BWSSB PRO Manjunath said the theme park is open on all days and has a help desk to provide further information.
BWSSB officials said they have been keeping tabs and imposing penalties on consumers who haven’t implemented RWH yet in their respective properties. In 2009, BWSSB had mandated RWH for all existing properties built on sital area of 2400 sq ft or more, and for upcoming buildings on sital area of 1,200 sq ft or more. The capacity of the RWH system should depend on the property dimensions – the total capacity should be 60 litres per sq m of roof area plus 30 litres per sq m of open area.
“We have been maintaining a database on RWH implementation and will levy penalty on property owners (who are not following the rules). The penalties have been increased recently. Over 40,000 properties are yet to implement RWH and the penalty levied on them comes to Rs 1.5 cr” said Rajeev. With further RWH implementation in outer areas, BWSSB estimates that 10 MLD (Million Litres per Day) of rainwater will be available for direct use in Bengaluru by 2025. As per their current estimates, about 2 MLD of harvested rainwater is being directly used (this is excluding the water being directed to the ground for recharge).
During the webinar, Asok Kumar from the Jal Shakti Ministry suggested to BWSSB officials to implement a incentive scheme for property owners who install RWH systems. BWSSB Chairman N Jayaram responded that BWSSB’s water supply was already heavily subsidised, but in the Board’s next meeting they would consider forming a policy on financial incentives for RWH installation. He added that the Board was already honouring those implementing RWH through its Jal Rishi Puraskara.
Asok Kumar also suggested to BWSSB to put up awareness materials on the Catch The Rain campaign at the RWH theme park, to publicise the campaign on water bill statements and on water tankers. Jayaram responded that these suggestions can be implemented.
[Watch the full recording of the webinar here ]