public water pump in central Kolkata

Can there possibly be a scarcity of water at the geographical location of Kolkata, in the world’s largest river delta?  As to judge from the first impression, this is not so. Public water sources are scattered around the city, with pumps and wells distributed along major roads, where the water mains run.

It is around these water sources that habitats and economies emerge. Families have installed shelters (which often double as vending spaces during the day), tea stalls and street kitchens cluster where water to wash their dishes is easily available.

The other interesting thing about Kolkata’s water distribution system is that the city has two separate networks (in addition to innumerable private borewells): One for filtered (drinking) water, and one for unfiltered river water, for washing clothes, flushing toilets, and the like. A grey water system at a city scale, owing to wise urban planning that foresaw the city’s future growth and water issues as the infrastructure was first built?

The very idea of constant, publicly accessible water supply is one of exemplary social ideals, and the separation of filtered and unfiltered water systems for different types of use has great ecological benefits. Intelligent as this system may seem, it appears that it is causing so many problems today as to make the city plan to quit the distribution of unfiltered water completely. Due to leakages in the ageing pipes, the drinking water is often contaminated, officials claim, therefore endangering people’s health. Also, many of the poor do not distinguish between the hand pumps, delivering filtered water, and the wells, delivering unfiltered water, when they fill their cups for drinking. And it is no secret that the Hooghly river, especially so at this downstream location, is highly polluted.

If the secondary water supply was cut off, however, this would not only exacerbate (future) water scarcity, but many people would be left without access to water for their non-drinking needs.

According to official statistics, the city today has a supply of 202 litres of drinking water per person and day. That is more than twice the per capita amount available in Mumbai. Yet Kolkata is growing, and groundwater is exploited to the extent it gets contaminated with saline water in many areas. The city is starting to think about water supply as a problem, and to plan for new ways to deal with this situation.

In this context, it would be a huge mistake to neglect the existing secondary system of river water pipes. Fresh water pipes need to be proofed against leakages, whether the source of contamination be unfiltered river water, stormwater runoff, or sewage. And there is a huge potential the existing system could be used in innovative ways for grey water storage, by interlinking both networks as to feed grey water back into the pipes after usage, therefore reducing not only fresh water demand, but also sewage loads.

This, for Kolkata, might be one important – and inexpensive – component of absorbing growth in water demand in a sustainable manner.

water pipes delivering water to the city

Mumbai and the reservoir lakes (marked blue)

1. How does water shortage impact the lives of people of diffrent social and income groups in Mumbai?

2.How do Mumbaikars deal wth this issue in their daily lives? What is their attitude towards it?

3. What is the city’s strategy at present?

4. Could the problem be assessed at a micro scale?

5. What are simple and cheap means for rainwater harvesting and greywater reuse?  Can they be integrated even in very small living spaces?

6. What would this mean at a city scale?

Mumbai’s water supply comes from 6 reservoir lakes that store rainwater collected  during rainy season: Vihar lake, Tulsi lake, Tansa lake, Upper Vaitarna, Lower Vaitarna, and Bhatsa. The city draws from the Mithi and Thane watersheds.  No additional capacity has recently been added despite the current rapid growth in population of Greater Mumbai. 

These lakes are fenced and protected by armed forces to prevent possible terrorist attacks on the city’s water supply.

The issue however is less the source than the distribution of the water. Huge losses occur due to leakages of the pipelines, and due to illegal water connections tapping into these pipes. It is estimated that these two factors together account for the loss of 30 – 50%.

2009/10 marks a year of crisis because the monsoon rain of 2009 was very poor.

The supply per day is now about 3,450 million liters, with a demand gap of at least 400 million.  [all numbers taken from http://mobile.reuters.com/mobile/m/FullArticle/CECO/nenvironmentNews_uUSTRE5B22IQ20091203?src=RSS-ECO]

Per capita supply is dropping to an alarming 90l per person and day – scientists seem to agree that 100l is the absolute minimum one person requires.
[graph to follow]

Water therefore is now rationed in Mumbai, with residential water supply cut by 15% and commercial water supply cut by 30% for this season. This means that taps are only running between one and three hours per day, and supply will be cut off entirely for one day per week in each neighborhood soon in order to improve water pressure in the other parts of the city.

There is an obvious need for people to store as much water as possible.  Most houses have tanks installed on the roof, or above the bathroom.  Many people also fill drums, metal kitchen vessels, or canisters during water hours. The results are ever lower water pressure during supply hours, and even actual fights, especially in places where several families share one tap.

Whoever can afford it can buy more water from water tankers that are now omnipresent in Mumbai.  The question, though, remains where they go to fill up.