Treating wastewater may help ensure Bengaluru’s water security

With water crises looming over the city, experts say that wastewater should be made available for tertiary purposes like construction and horticulture.

Despite the huge potential, poor standards, and lack of clear guidelines for commercial use have been hindering the city’s ability to utilise wastewater.

Analysis by a private research centre, WELL Labs, reveals that the city produces nearly 2,000 MLD of wastewater. Of this, only 655 MLD or just 32 per cent is being reused.

"The use of treated water is the way ahead,” insisted V Ramprasad, co-founder and convener of the NGO, Friends of Lakes.

“Bengaluru cannot fully depend on Cauvery. To ensure we have groundwater to fall back on, we must prevent groundwater exploitation and use treated water for construction and horticulture purposes,” he added.

He highlighted numerous occasions when borewell water would be used in construction sites, severely depleting water levels. "Residents moving to homes constructed using borewells would lose water security," he explained.

Of the 2,000 MLD, the Bangalore Water Supply and Sewerage Board (BWSSB) treats nearly 1,240 MLD. But it hasn't been able to get many to buy the treated water.

"We have been trying to encourage the use of treated water. It is cost-effective and can greatly ease the situation. Currently, we supply treated water to the airport, the Karnataka Power Corporation Limited (KPCL), and a few industries. Talks are on to get more industries on board,” a senior BWSSB official said.

At the same time, nearly 30 per cent of the wastewater treated at decentralised Sewage Treatment Plants (STPs) set up at apartment complexes and commercial establishments is mostly let into lakes in the absence of clear guidelines on selling treated water.

"There is a great potential to use water from decentralised STPs,” pointed out Shreya Nath, managing partner, Urban Water Programme, WELL Labs.

“For example, in earth excavation and other construction activities, freshwater is being extensively used as a dust suppressant. We could reduce the dependency heavily if we can use treated water for such purposes," Nath said.

Vikram Rai, general secretary of Bangalore Apartments’ Federation, said that many apartment societies were open to reusing and selling treated water, but were held back by the absence of clear guidelines.

“We are working closely with the BBMP to see if we can supply water to its parks for horticulture purposes. But this is seasonal,” he said.

“The other option is to sell treated water. We need a policy and clear guidelines for this. If it is commercially viable, more apartment complexes will come forward,” Rai added.

A lake activist was concerned about water treated at STPs set up by the BWSSB. "The construction industry and the public need assurance from the authorities that the treated water meets the standards,” he said, calling for better monitoring and treatment system following recent incidents of lake pollution caused by water released from STPs.

At a glance 

Total wastewater generated: 2,000 MLD
Treated in centralised STPs: 1,240 MLD
Treated in decentralised STPs: 615 MLD
Untreated: 145 MLD

Outflow

Gardening:13 MLD 
Toilet flush: 125 MLD 
Lakes: 1,192 MLD 
Agriculture and industries: 530 MLD

(Source: WELL Labs)