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Managing wastewater

About 80 % of the fresh water consumed in a house goes out as used water or wastewater. Considering the city consumes around 1,400 million litres from the Cauvery water supply alone, and perhaps 400 million litres from borewells, about 1,440 million litres of wastewater is generated daily.

The city simply does not have the capacity or the network to collect, convey and treat this volume of wastewater.


The Bangalore Water Supply and Sewerage Board (BWSSB), through a notification dated March 3, 2016, has made it compulsory for any building consisting of more than 20 houses or apartments or flats to have its own modular sewage treatment plant and dual plumbing lines to use this treated water for flushing the toilets.

This is applicable to both new buildings and old ones within the jurisdiction of the Board, meaning if you have a connection to either the water or sewage lines or are considering one, then this is applicable.

The city already had a precedent of decentralised wastewater management systems being made compulsory with the Karnataka State Pollution Control Board insisting on such systems for apartment complexes with more than 50 flats or consuming more than 50,000 litres of water per day as part of their consent for establishment and for residential apartments with built-up area greater than 20,000 sq. m in all areas, 5,000-20,000 sq. m in unsewered area and commercial establishment in excess of 2,000 sq. m.

This is happening since 2006 and has resulted in more than a couple of thousand WWTPs being set up in apartments in the city, making it one of the largest such systems in the country.

The KSPCB also insists on reusing the entire treated wastewater within the complex, a concept called zero liquid discharge.


Things have not gone right with the old laws itself. Most of the WWTPs set up were dysfunctional or not meeting the standards required for treatment and release of wastewater. The zero discharge norms was impossible to meet as has been pointed out by experts such as Ananth S. Kodavasal.

A committee was formed to look into the functioning of the WWTPs and a report highlighting the issues was submitted to the Board. This clearly highlighted that it did not make sense for decentralised WWTPs to be set up in areas already covered by the BWSSB’s sewerage network.

Yet the BWSSB learns no lessons from past experience and mandates more of the same WWTPs.

To add to the problems the Central Pollution Control Board and now the KSPCB has upped the standards of treatment of wastewater and reduced significantly one parameter — the Biological Oxygen Demand — from 20 mg/l to 10 mg/l.

In the absence of a wastewater management policy, ad hoc decisions are made both by the service provider mandated for the job — the BWSSB — and the regulator to ensure that the actors and stakeholders perform according to rules and regulations and standards laid down by the law- the KSPCB.

On the one hand, the environment, especially our lakes, is being polluted and on the other hand, impossible conditions are being made law for building complexes.

Excellent guide

‘The STP guide – Design, Operation and Maintenance’ authored by Ananth S. Kodavasal and published by the KSPCB has been published and is available on the net ( ).

This lays out how wastewater can be managed practically and not ideally. This should form the basis of any policy document on wastewater.

It is time that we revisit the entire management system of wastewater and come to a coherent policy and action.

Else, both scarce resources and the environment will continue to be under threat. Learning quickly from experience is water wisdom.

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Printable version | Oct 30, 2020 10:18:18 AM |

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