Harvesting rain

Financial Times

May 27, 2009

Poonam Bisht may be the best-known resident of West End, an affluent neighbourhood in New Delhi. The housewife and mother of two is the suburb’s resident activist. Ms Bisht’s most ardent campaign has been for the building of a rainwater harvesting system in the neighbourhood. The low-tech system consists of a network of unassuming gutters in the ground that funnel rainwater to shallow pits lined with pebbles that act as a filter. The water then drains deep into the ground via a pipe to replenish the groundwater that West End relies on. Thanks to this system, West End is able to draw on its own tube wells and no longer hires trucks to bring in water, as is the norm in many Indian cities where groundwater has dried up.

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Water shortages plague India. Some 170m people lack access to safe drinking water and 70 per cent of the country’s population of 1.1bn do not have adequate sanitation, says Oxfam India. Rainfall differs dramatically from region to region but the annual monsoon provided an average of 922mm of rain in India in 2007, according to the Indian Institute of Tropical Meteorology. Yet little of that is captured. A law was passed in 2001 that required all new buildings to have rainwater harvesting systems but it has gone largely unenforced.

Delhi, one of India’s richest cities, “faces an unparalleled water crisis”, according to the United Nation’s Delhi Human Development Report 2006. About 45 per cent of the city’s 16m residents have no sewage services, meaning raw sewage is dumped into rivers. Pollution of water sources leads to the drilling of private wells, which is rapidly depleting groundwater, or else trucking in water from distant treatment plants.

In contrast, the southern city of Chennai has shown that political will can prevail. In 2005, the drought-prone city decided to tackle its constant water shortage by requiring all buildings to install rainwater harvesting systems within four months. Enforcement was strict. The government threatened to turn off the water supply unless proof of water harvesting systems was produced by building owners. As a result, Chennai now has a water surplus. Thousands of trucks that used to criss-cross the city delivering water have moved to other states. “You need a government with will,” says Salahuddin Saiphy, a hydro-geologist and assistant co-ordinator of the Centre for Science and Environment’s water programme.

Ms Bisht studied rainwater harvesting at the Centre for Science and Environment (CSE), a non-governmental organisation in Delhi, and used funds from West End’s neighbourhood association and a city grant to pay for her area’s system. But she also went door to door to collect Rs2,000 ($41) from every household to pay CSE contractors to build the Rs380,000 system. Even though West End is filled with large homes and expensive foreign cars, people were reluctant to contribute. But Ms Bisht persisted and now West End is one of a handful of neighbourhoods in Delhi with a collective rainwater harvesting system.

CSE is best-known for pushing through landmark anti-pollution legislation that requires all commercial vehicles in Delhi to run on natural gas – a feat many had thought impossible. And since 2005, the centre has held more than 40 rainwater harvesting workshops for engineers, architects, urban planners, real estate developers, non-profit organisations and concerned citizens.

Mr Saiphy of CSE says that in the past five years, the centre has given technical help to more than 1,000 rainwater harvesting projects across India. Model systems in the Delhi area include those at the Bhutanese embassy, a Hero Honda motorcycle factory, the Indian Spinal Injury Centre and the Mira Model School.

CSE workshops give an overview of the different types of rainwater harvesting systems such as storing rain in tanks versus replenishing groundwater. They also analyse costs and return on investment and survey existing models across India, including historic examples.

One recent workshop included a field trip to observe traditional rainwater harvesting systems in Mehrauli, south Delhi. Hauz-e-Shamshi was once a magnificent reservoir built by King Shams-ud Din Iltutmish in 1230. Rain was the main water source for the reservoir, which once sustained the whole city. Today a domed pavilion overlooks a sewage-filled pool of stagnant water. Though such systems have fallen into disrepair, CSE hopes that modern versions will come into vogue.

The benefits are clear. At CSE’s office in south Delhi, a Rs30,000 rainwater harvesting system of rooftop gutters and trenches in the ground captures 366,000 litres of rainwater a year in the 1,000 square meter plot. That means CSE captures about 60 per cent of the rainfall that falls on its premises. The cost of installing such systems ranges between Rs2,000-Rs30,000 for buildings of about 300 sq m. Maintenance fees to clean the filters are about Rs200 a year.

In some parts of India, rainwater harvesting is a matter of survival. Mewat district is only 70km from Delhi but it is 100 years behind in terms of living conditions, says Lalit Sharma, head of the water programme at the Institute of Rural Research and Development (IRRD) near Delhi. Out of 503 villages in Mewat, only 63 have fresh groundwater.

Mr Sharma cites the example of Karheda, a village in Mewat where groundwater had become so saline that it could not even be used for mud-plastering or boiling lentils. Women had to walk 3km-4km each day to fetch water from another village and disputes over water were erupting between Karheda and its neighbours.

But in 2005, IRRD installed a system to recharge groundwater at a cost of about Rs20,000. Within a short time, Karheda was able to use its groundwater. Today, water is available year-round in the local school after a 20-year absence. “They are much better off,” Mr Sharma says. But he warns that similar measures must be taken on a larger scale to avoid water depletion across Haryana. “If the situation doesn’t get corrected, after 15-20 years the same thing will happen here.”

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