Every summer discussions in Delhi revolve around one word -- water or rather the lack of it. Citizens, almost unfailingly, lash out at the incompetence of the government to provide clean, potable water. The government, religiously, promises the sky. While charges and counter-charges are traded, concrete steps are put to the backburner. Now, experts are proposing sustainable systems like rainwater harvesting to mitigate this problem.
The need to harvest water in Delhi is manifold. First, surface water in the capital suffers in terms of quality and quantity. This has increased pressure on groundwater resources, leading to a marked decline in the ground watertable in different parts of Delhi. The average decline of water table during the last decade was about 0.4 metre per year. The problems do not end here. The groundwater is brackish and the river Yamuna, a major source of freshwater to Delhi, contains pesticides and chemicals like aldrin, dieldrin, heptochlor, bhc and endosulphan. Some of these are organochlorines, which are known to cause cancer. These are present at levels that far exceed permissible limits.
Thus, with no solution in sight for the augmentation of raw water supplies by conventional means, the only option is to capture rainwater where it falls. This also makes ecological, financial and political sense while promoting community and household-based water harvesting systems. To understand the efficacy of such an initiative, it is important to look into the experiences of Chennai, where water harvesting has proved to be effective.
Metro Water was quick to realise the importance of saving coastal aquifers and other groundwater potential zones in and around the city. An act to regulate and control extraction, use or transportation of groundwater was passed in 1987. To complement these strategies and following the 1993 drought in Chennai, Metro Water took initiatives to harvest rainwater both at the macro and micro level. At the macro level largescale recharging of water sources like injection wells and check dams were undertaken to overcome sea water intrusion. At the micro level, along with Chennai Metropolitan Development Authority ( cmda), cmwssb made rainwater harvesting structures compulsory for multistoried building plans which have been submitted for approval since 1997. It is estimated about 500 complexes in Chennai have rainwater harvesting systems. Though this is not mandatory, both agencies ensure that the structures are constructed before the water supply and sewerage connections are provided to these buildings.
In the initial stages, the response from the builders was lukewarm. But a sustained campaign evinced positive responses from the construction industry.
There have been efforts in Delhi to harvest rainwater. The Central Ground Water Board ( cgwb ) conducted pilot projects at the Jawahar Lal Nehru University ( jnu ), the Indian Institute of Technology ( iit ) and in residential areas of Malviya Nagar. Check dams and rooftop water harvesting structures were installed at jnu . These efforts resulted in a rise in water levels in a radius of 60m from the dams. The total storage capacity of 49,000 cubic metres was created in these four dams and 1,25,000 cubic metres had already been restored to the aquifers. In addition to this, capacity utilisation up to 300 per cent has already been achieved in one of the dams.
In 1998 , about 8,00, 000 litres of water was harvested from rooftop structures covering 1,666 square metres at iit.
In March, intach tabled a blueprint on water augmentation through water harvesting and recycling within Delhi. According to the report, water harvesting and recycling will yield 675 mld and 2,205 mld, respectively. This amount together is sufficient to close the projected demand-supply gap at affordable costs. intach proposes to augment water supply by 9.8 lakh million litres per year through rooftop water harvesting and other harvesting techniques. They also plan to use paleo-channels, village ponds and local eco-parks to harvest water. The Central Ground Water Board ( cgwb ) will extract and refill the unconfined aquifer group underlying the Yamuna floodplains. The first phase of the scheme is expected to supply Delhi with an additional 900 mld of water at a cost of Rs 25 crores. Pani Morcha, an ngo , has proposed to treat 70 cusecs of sewage water that will be pumped into the river Yamuna.
Moreover, these schemes remain technocratic. For example, storing water in drainage channels and flood plain reservoirs may require resettlement of slumdwellers. This can have political repercussions. Secondly, the quality of water should be ensured. Thirdly, the efforts to dewater and refill the unconfined aquifers in the Yamuna basin requires efficient coordination between departments.
What we require now is to ensure these measures are coupled with localised water harvesting systems to ensure an equitable and adequate supply of water.
The cost of rainwater harvesting at a local level will vary from Rs 5,000 to Rs 20,000. The cost will drop with the increase in number of houses. The government can promote these systems through policy incentives similar to those in foreign countries (See: How the World Manages its Water Resources ).
Cooperation among owners is important. K R Gopinath, who has been involved in rainwater harvesting says, "In housing complexes differences among society members hinders the promotion of rainwater harvesting."
On the other side of the spectrum is Madeline Court at Arumbakkam where residents of 16 flats collected Rs 1,000 to harvest rainwater with very little treatment.
The question of water rights can prove to be a dampner for the whole process. This is because water harvested by few may not benefit the initiators. "This acts as a hindrance for interested clients,"says Indukanth Ragade of Alacrity Foundation in Chennai, a construction firm which specialises in water harvesting structures.
Reported by KumKum Das Gupta, Indira Khurana and Saravanan V S.