Water efficiency I: Cities
by Sekhar Raghavan
The Indian city of Chennai receives abundant rainfall during the monsoons but is still water-starved due to over-exploitation of groundwater. One possible solution, as outlined here, is to implement widespread urban rainwater harvesting for aquifer recharge.
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Yet, 60% of India is expected to be living in towns and cities by 2025. Municipal authorities are finding it more and more difficult to meet the water needs of this bourgeoning urban population. A classic example is the coastal city of Chennai (Madras), one of the four major metropolises of India and the capital of the state of Tamil Nadu. Inadequate supply of municipal water over the last two decades has forced the populace to relentlessly tap groundwater for its needs. This over-exploitation has resulted in the sharp depletion of the groundwater table and to deterioration of its quality as well. In Chennai's coastal suburbs in particular, seawater has already intruded into the coastal aquifers, rendering groundwater quite saline.
Many other cities, both in India and elsewhere, are already facing a similar situation or heading towards it. India, with its bounteous monsoon rains, can substantially alleviate the problem by artificial recharge of the groundwater in areas like Chennai, where the underlying sandy soil and aquifer structure is suitable for such purposes. That is, after rainwater has been gathered by efficient and cost-effective RWH structures throughout the city, it can be systematically injected into the soil by means of equally cost-effective wells and other infiltration structures. Urban rainwater harvesting is of a more recent origin than rural water harvesting; new designs will have to be developed for the urban context, particularly for RWH systems that are primarily concerned with aquifer recharge. But progress made to date in Chennai indicates that such changes are indeed feasible, cost-effective, and potentially quite effective for other similar urban locations.
Promoting urban RWH involves three components:
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The campaign's primary objective was to create awareness about the importance of rainwater harvesting. It was explained to the residents that implementing rainwater harvesting in these sandy-soiled areas would be very simple and cost-effective as well as being an excellent tool for preventing seawater intrusion into the aquifer. This is especially germane in cities like Chennai, where many people live in multi-story apartment complexes that depend on individual wells, rather than a municipal water system, for both potable and non-potable water uses. However, the concepts being new, the initial response to these ideas was none too encouraging; residents were reluctant to invest in rainwater harvesting systems. It took almost three full years and the help of the print media -- especially neighborhood newspapers -- to convince the residents of the need and relevance of RWH in a city like Chennai.
In order to accelerate these activities, a few like-minded people formed the Akash Ganga Trust in January 2001. Taken together, "Akash" ("sky") and "Ganga" (the perennial river Ganges of North India, believed to have descended from the sky) mean "water received from the sky," or rainwater. On August 21, 2002, the Trust launched Chennai's Rain Centre, inaugurated by the Honorable Chief Minister of Tamil Nadu. The Rain Centre, the first of its kind in the country, is a one-stop information and assistance center on rainwater harvesting. The initial seed money for the center came from a few non-resident Indians living in the U.S. Further support, in the form of resource material, was provided by the Centre for Science and Environment, an NGO headquartered in New Delhi. The state government of Tamil Nadu is also one of the co-sponsors of the Rain Centre.
In addition to Akash Ganga Trust, a few other NGOs like Exnora, Rotary Clubs, Lions Clubs and INTACH (Indian National Trust for Art and Cultural Heritage) have also been playing an active role in promoting RWH in Chennai. Particular mention must be made of the efforts of Rotary International District 3230 in renovating and reviving seven temple tanks for use in artificial recharge of the harvested rainwater, besides creating awareness among its members.
The Rain Centre has been involved in all the three thrust areas defined above (education, implementation, and evaluation/research) since its launch almost two years ago. The Centre, which is open to all, charges no fee for its services to the citizens. Its activities, carried out thanks to the funds received by the Akash Ganga Trust through donations, are summarized below.
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In December 2001 and August 2002, the Centre conducted two training workshops in RWH, specifically aimed at plumbers. Advertisements in both vernacular and English language newspapers requested plumbers to apply, with the incentive of having jobs after the workshops. The trained plumbers were thereafter sent to different areas of the city to advise residents on RWH design and implementation costs. After the state government made RWH compulsory in October 2002 (as explained later in this article), several more newspaper articles about RWH also mentioned the Rain Centre with its offer of free advice and assistance through trained plumbers. During the following year the Centre received several hundred calls requesting such help.
With the assistance of these trained plumbers, RWH was directly implemented in more than 1000 premises; an equal number of residents were provided with advice on getting it done with their own plumbers. Though this may appear to be a small fraction in the total number of households in Chennai, it has had an important "ripple effect" in spreading the correct methodology.
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The colony chosen for the survey, Gandhi Nagar, comprises 309 contiguous plots occupied either by independent houses or multi-story apartment complexes. The survey revealed that all but 2 of the 309 residences had installed RWH structures. However, only 30% of the systems installed were extremely well-designed; another 20% of the installed systems were adequately/reasonably designed, and the remaining 50% were not well designed. These poorly designed systems proved to correlate strongly with households whose residents were not convinced of the importance of RWH, but only installed systems to comply with the law.
Another survey examined how citizens are managing their water needs for both potable and non-potable uses, particularly in light of Chennai's current rain deficit. Results were particularly useful given the Rain Centre's interest in educating people about wastewater reuse and recycling, water usage and conservation, composting toilets, and so on. The findings, published in the local English newspapers, revealed that people are not only learning to live with less water, but also with different qualities of water for a) drinking and cooking; b) bathing and washing; and c) toilet flushing. However, due to failure of the northeast monsoon in Chennai during 2003, assessment of the post-monsoon and post-harvesting effects on quality and quantity of groundwater, for establishing the benefits of rainwater harvesting, was deliberately left out of the scope of the survey.
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As another water conservation measure, the Rain Centre also proposes to promote awareness about the importance of water reuse. Water that is used for bathing, washing clothes, vessels, vegetables etc., is generally referred to as "sullage." Currently, this sullage, typically 50 - 60 liters per day per person, gets mixed with sewage (water from toilets) and sent to sewage treatment plants for treatment. However, sullage does not need the degree of treatment that sewage does; it could be easily and economically purified of organic compounds and either directly reused or recharged into the groundwater. The Centre is committed to working towards policies and techniques that will promote this separate treatment and usage of sullage water and sewage water in future.
In addition, the Rain Centre is offering its help and expertise to set up similar centers in other cities in India and is also conducting a survey to select cities in other countries where RWH for large-scale groundwater recharge would be relevant.
The Trust is also interested in setting up, at its own cost, RWH systems in charitable organizations such as old age homes, orphanages, homes for the physically and developmentally disabled, and homes for destitute women. Since these are basically service organizations depending on donations from concerned individuals and corporations, they are often unable to afford the financial outlays needed for the installation of RWH systems. At the same time, these organizations require large quantities of fresh water both for potable and non-potable uses; therefore, they can have a very important role to play in sustaining local groundwater sources through the practice of RWH.
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Since May 2001, the government of Tamil Nadu has promoted awareness about RWH throughout the state by putting up posters inside and on the back of buses as well as in public places; preparing and distributing pamphlets and brochures in Tamil and English; and producing and screening videos on RWH. In addition, a publicity van was specially made by the Chennai Corporation to propagate RWH in various localities of Chennai. Similar Rain Centres were started in two more Chennai neighborhoods, one by the local-level and one by the state-level water authorities. Others were started in the offices of the District Administrative heads of all the 27 districts of the state.
At the national level, school and college students have been involved in RWH awareness-raising campaigns in small towns through the National Service Scheme (NSS), a government-supported activity in colleges and polytechnics. They have also been involved in rallies carrying placards about the importance of RWH.
The Tamil Nadu government enacted a law in October 2002, followed with an ordinance in June 2003, making the implementation of RWH systems compulsory in all existing buildings in the entire state of Tamil Nadu by October 11, 2003. The law mandates that "waste water from the bath and wash basin shall be treated by organic or mechanical recycling and taken to a sump for onward pumping to an exclusive overhead tank for use in toilet flushing. Any excess shall be connected to the rainwater harvesting structures for groundwater recharge."
Further, Tamil Nadu's Groundwater Regulation Act of 1987 has also been amended to include the power to grant or refuse groundwater licenses. Use of groundwater for gardening, for private swimming pools and for non-potable uses by industries has been banned. Those who are found guilty will be fined Rupees (Rs.) 2000/- for the first time and Rs. 5000/- for the second time; these substantial amounts are calculated to have a strong deterrent effect.
To show that it not only preaches but also practices, the government
also issued orders to all its departments to implement RWH in buildings
belonging to them. The Chennai Corporation has implemented RWH in public
places like roads that get flooded during monsoon, schools, parks and
their staff quarters.
Chennai's Metrowater Department, which is responsible for operation and maintenance of the entire water and sewer system within Chennai, has conducted free workshops on RWH implementation techniques for all interested. It has especially focused on training for unemployed diploma holders, who are subsequently listed as resource persons for carrying out RWH in houses/flats. To date, however, the government has not carried out any surveys, such as those conducted by the Ashoka Ganga Trust, to ascertain the efficiency of the RWH systems implemented by Chennai residents.
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The need of the hour is to spread the message of RWH as widely as possible, from neighborhoods, to cities, to entire countries. This, I am convinced, can best be achieved by carrying out awareness-raising campaigns and by setting up more Rain Centres across the length and breadth of every country as a mass movement. Cities throughout the world, which are water-starved but not rain-starved, will have to be identified and selected for this purpose. I would like to conclude by emphasizing again that water harvested is water produced. Our slogan for the future should be: HARVEST RAINWATER LEST WE PERISH.
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Editor's note: On 26 December 2004, Tamil Nadu and Chennai were hit, like so many other locations in Asia and Africa, by the devastating tsunamis resulting from a powerful earthquake off the coast of Sumatra. In light of this natural disaster, Mr. Raghavan offers the following addendum to his article:
In India, the coastal districts of Tamil Nadu were very badly hit by the tsunamis; more than 10,000 people have died. A particular concern for the Rain Centre is how the tsunami may have affected the area's coastal aquifers:
The last possibility is the most worrisome in terms of possible effects on groundwater. The amount of damage would depend on the quantity of seawater percolating into the aquifer, the pre-tsunami quality of the groundwater and the depth of the water table.
In order to conduct a survey to quantify the tsunami's potential effects on groundwater, pre-tsunami baseline data would be required, including the depth of the groundwater table and the quality of the groundwater. For Chennai, few baseline data are available except from the few government monitoring wells, which are monitored monthly. We at the Rain Centre propose to collect these data from the concerned government department and monitor them for at least the next year, in order to determine what effects the tsunamis may have had on the local groundwater.
If it proves that the water quality of coastal aquifers has been adversely impacted by the tsunami, RWH can help reverse the damage: through focused recharge of such aquifers with pure, harvested rainwater, the brackish water will be diluted and the water quality will be restored to that of pre-tsunami days. To the extent that such steps are required, the Rain Centre will support them to the utmost of its ability.
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Dr. Sekhar Raghavan, an Ashoka Fellow, is Director of the Rain Centre. He can be reached for comment by email at email@example.com or by post at the Rain Centre address:
4, 3rd Trust Link Street,
Chennai 600 028, INDIA
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Akash Ganga - RWH: Rain Centre
Web site of Chennai's Rain Centre
Harvesting the rains!
This 2002 article from rediff.com India provides more background on Akash Ganga and the Rain Centre.
This web site from Chennai Metrowater contains extensive information on rainwater harvesting.
Produced by the Center for Science and Environment, a New Delhi-based NGO, this site focuses on rainwater harvesting in India but also contains information of interest to rainwater harvesting practitioners elsewhere.
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