Recycle Water: Does Bangalore face Waterless Future? – Final Part

In final part of “Does Bangalore face Waterless Future?” series presented by ApnaComplex, Mr. S.S.Ranganathan elaborates on “RECYCLE” parts of his “REDUCE, REUSE and RECYCLE” mantra for Water Conservation. He explains how technology can help recycle waste water to potable water.
Looking for earlier parts fo this series? Read Part – 1 and Part – 2.


Reuse of water is possible when you consider that the water used in a washing machine can be collected and used to flush toilets.Of course, this becomes very difficult and cumbersome in an apartment.It is possible without much difficulty in a bungalow, so this
aspect  is not going to be discussed further.


In the present context, this means that water used and therefore contaminated is subjected to treatment and thereafter used for uses other that drinking , cooking and bathing/washing. Water used by humans emerges with contaminants like soap/detergent/cleaning chemicals, oil, grease from the kitchens and bathrooms due to its use for washing and bathing. This water is referred to as “sullage” or “grey water”. Whereas, water used to flush toilets results in what is often called “ black water” but commonly known as “Sewage”. On an average 75 to 80% of water used by a human in a residence emerges as waste water. In an apartment/gated community, both these waters come out of the buildings/villas through separate pipes, but, are combined and taken to a Sewage Treatment Plant(STP).

Grey water is easier to treat than sewage, but, since in most places space is expensive, it is combined with sewage and treated in an STP. In a majority of cases, fresh water is used by the resident in a building to flush toilets with fresh water whereas, toilet flushing does not need  water that is good enough to drink. It is essential therefore to install a well designed STP and install separate tanks on the roof of each building with dedicated plumbing for toilet flushing, gardening and washing of cars, yards /roads, etc. Recycling is capable of reducing fresh water demand by as much as 50%.

The island nation Singapore has no fresh water of its own, but gets water piped in from neighbouring Malaysia. In anticipation of a possible stoppage of water by Malaysia, Singapore has build STPs with ‘ polishing treatment’ using a process called ultrafiltration which makes purified sewage fit to drink. This treated sewage meets as much as 30% of the drinking water demand of Singapore and is even sold as bottled water with the name “ Nuwater”. I have personally brought bottles of this water back to India and used it for drinking. The technology is available in India too, but it does not come cheap.

I often get questions asking what is the ROI (return on investment) with these investments in having proper STPs, proper plumbing and technology. My answer is that such a question is irrelevant when there is no fresh water to drink! The only alternative is to die of thirst? What would you prefer?

About the author
S S RanganathanMr. S.S. Ranganathan, author of this series of guest posts, is a retired senior executive of Ion Exchange and currently a freelance Water Management Consultant based in Bangalore. His blog at “India Water Portal” explains the work he does in detail. He can be reached at +91-93437-34229.

This article aims at providing information for benefit of ApnaComplex customers and blog readers. The thoughts and opinions expressed here are solely of Mr. S. S. Ranganathan and NOT of ApnaComplex or its representatives. We suggest to post your queries or comments below and Mr. Rangathan can answer them at his convenience.
  1. A.S.Belur

    we have an stp for 100 flats, but no road drain to allow final treated effluent. How profitably can the final effluent be used?