Many residential societies in Bengaluru are now on the lookout for innovative ways to conserve water amid the ongoing crisis. The focus is mainly on the reuse of discharged wastewater from RO filter systems and sewage treatment plants (STP).
One of the methods which has proven effective for these societies is using the wastewater discharged from RO water filters in a centralised manner to reap greater benefits.
For instance, after the Bangalore Water Supply and Sewerage Board (BWSSB) issued an order saying that drinking water should not be used for non-potable purposes, Aristocrat Apartments at Kasturinagar came up with a way to collect around 600 litres of RO wastewater every day.
“We first did a survey in the apartment and found that out of 145 units, we can get around 10 litres of RO wastewater every day from around 70 units. We gave them 10-litre cans to fill and keep outside their houses. This water will then be poured into two 200- litre drums which we have bought. By fitting taps and hose to those tanks, we can use that water for car washing, mopping of common areas, and for plants,” said Rohini Ghose, secretary of the apartment association.
She added that as they are left with some spare water after utilisation, they have sent the samples to a NAPL-accredited laboratory to see if all the required parameters are met to use it for other purposes such as topping up swimming pools.
Apartments which had employed unique conservation methods even before the crisis struck are now sharing their ideas to help other societies conserve water.
Krishnanagar Apartments at Vimanapura has connected the RO waste discharge systems from all houses in a centralised manner to let the water into rainwater harvesting (RWH) pits.
“Per day, we can conserve up to 6,000 litres of water with this method at a mere material and labour cost of ₹3,000. While the treated water from the RWH pits can be used for non-potable purposes, as the RWH pits are close to our borewells, it can also help in recharging the groundwater which could be beneficial to everyone in the vicinity,” said an ex-committee member from the society.
At Sobha Classic in HSR Layout too, the centralised RO system has reduced the wastage of water. “Individually, for every eight litres of water that is filtered for drinking, 25 litres are wasted. But as we have this centralised system, the loss is only 25%,” said Sreejith Govind, a member of the apartment’s managing committee.
Selling STP water
While most apartments use STP water for flushing, gardening, and cleaning purposes, some apartments have found a way to ensure the water that remains after their usage does not go to waste.
“After our usage, we used to pump around 50 KLD STP water into the drain. Hence, we tied up with a private company which converts STP water into potable water. Since many might not be comfortable with consuming such treated water, it can also be bought back by the apartment and used to fill swimming pools or for other such uses,” said Jubin Thomson, secretary of the apartment welfare association.
