Water Woes in Chennai: Quick Comments on RWH and Desalination

In a recent post I had discussed the potential for desalination as a solution to shortages of water and had made a reference to Chennai. The intention was not to discuss the water problems of the city at any length. The city’s water woes are well known but not well studied.

One attempt to redress the lacuna is the work of A. Vaidyanathan (done jointly with J. Saravanan). Readers may read the relevant chapter in this book. Based on a survey of households carried a few a years ago it provides information on several aspects such as consumption, sources of supply and costs. Care must be taken in interpreting and drawing conclusions from the study as it had several limitations, which the authors themselves highlight. It does provide a broad overview of the water issues including discussion on conservation, rainwater harvesting (RWH) and other supply augmenting measures.

While the work is useful it lacks conceptual clarity. If suffers from most of the errors I had pointed out in an earlier post. We don’t get a water balance for the city that would take into account the way water is received, stored, used and disposed.

For example, while discussing RWH the authors don’t tell us where does the water go if it is not harvested. Does it flow out to the seas or to tanks or lakes that dot the city or in to the marshes or other natural bodies? Does RWH increase overall water availability or does it just redistribute it? Does local availability increase? Is it a zero-sum game?

(This is an important issue especially in urban areas. In rural areas local harvesting has much stronger rationale though the issues are relevant there too. See, 1 and the responses to it - 2 and 3.)

There is also the issue of RWH on individual structures. Even if water is to be harvested locally must it be done on each and every building rather than in a collective enterprise? Making RWH compulsory as was done in Chennai is also likely to lead to corruption, or people putting up token structures that are not effective to begin with or then failing to maintain them.

Desalination is dismissed in one paragraph, which is surprising as the book has been written in 2006 by when a lot of initiatives in Chennai had been taken up. As mentioned in an earlier post this augmentation measure may have great potential and impact.

Chennai is interesting not only because it suffers acute and chronic water problems; relies on water from surrounding and far-off areas with attendant problems; but also because it is on the coast where desalination can be an attractive proposition.