Bengaluru: With no system in place to store or transport treated water, hundreds of apartment complexes in the city continue to release it into storm-water drains (SWDs). A much-publicised agreement signed last year between Bangalore Water Supply and Sewerage Board (BWSSB) and Bangalore Apartment's Federation (BAF) to promote the reuse and sale of treated water has failed to take off.
The pact, announced in April 2024, was intended to turn treated wastewater into a resources Apartments were allowed to sell surplus treated water at Rs 8 per kilolitre, as BWSSB would buy it at Rs 10, retaining retaining Rs 2 as service charge. However, neither a functional supply network nor a dedicated fleet of tankers has been created to move the water from apartment treatment plants to industries, parks, or construction sites that could use it.
As a result, apartment associations say they have no option but to let treated water flow into the city's drains. "On an average, our apartment treats 85 kilolitres every day, of which at least 45 kilolitres of water remains after usage for maintenance, gardening, and other needs," said a resident of a 100-flat complex in south Bengaluru. "It's good that BWSSB made sewage treatment plants mandatory, but they must also take responsibility for what happens after treatment.
As a result, apartment associations say they have no option but to let treated water flow into the city's drains. "On an average, our apartment treats 85 kilolitres every day, of which at least 45 kilolitres of water remains after usage for maintenance, gardening, and other needs," said a resident of a 100-flat complex in south Bengaluru. "It's good that BWSSB made sewage treatment plants mandatory, but they must also take responsibility for what happens after treatment.
We can't store such large quantities of water, so we end up releasing it into SWDs. Many apartments across the city do the same."
In Mahadevapura, a 467-flat complex generates around 250 kilolitres of treated water daily, of which 150 kilolitres is reused. The remaining 100 kilolitres goes into drains for lack of space and options. "Even if we store the water, it will pile up within days. Without buyers or infrastructure, it becomes an impossible situation," a member of the residents' association said.
BAF, which represents more than 1,000 apartment communities across Bengaluru, attributes the deadlock to logistics. "We were unable to sell treated water due to the lack of tankers. The pact is still on paper," said federation president Satish Mallya. He added that many apartments aren't located near lakes where treated water could be discharged and that the federation has suggested allowing its use in govt parks for greening and maintenance.
According to BAF's estimates, Bengaluru produces around 350 MLD of treated used water from decentralised sewage treatment plants in apartments. However, about 24% of the city's wastewater remains untreated.
The estimated citywide demand for treated water is substantial — 175 MLD for flushing and landscaping, another 175 MLDfor industrial operations, and 100 MLD for cooling systems in data centres and tech parks. Yet, without an organised collection and delivery mechanism, most of this potential remains untapped.
A demand issue: Official
Interestingly, BWSSB chairman Ram Prasanth Manohar said the bottleneck lies in low demand rather than supply. "We have deployed 20 colour-coded tankers for treated water distribution to ensure there's no mixing. But demand is currently low because of good monsoon recharge and sufficient groundwater levels. Once the dry months begin, supply will be scaled up," he said.
Interestingly, BWSSB chairman Ram Prasanth Manohar said the bottleneck lies in low demand rather than supply. "We have deployed 20 colour-coded tankers for treated water distribution to ensure there's no mixing. But demand is currently low because of good monsoon recharge and sufficient groundwater levels. Once the dry months begin, supply will be scaled up," he said.
Officials added that treated water is also being directed to nearby lakes to aid groundwater recharge, though these efforts cover only a fraction of what is generated daily in apartments.
Environmental experts warn that continued discharge of treated water into SWDs undermines years of investment in decentralised treatment infrastructure and adds unnecessary load to downstream systems. With the city staring at growing water scarcity, unused treated water represents not just waste but a missed opportunity to build resilience.
