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Harvesting the rain

Siri BulusuSeptember 5, 2013

The populous Indian city of Bangalore could be running out of groundwater. A rain harvesting park shows how the growing population, especially its poorer residents, can help fill the gap.

Raindrop on a leaf
Image: AP

India's third-most-populous city is known for its booming tech industry and cosmopolitan culture. But poor planning and inadequate infrastructure has set Bangalore on a trajectory that could leave its residents lacking the most basic amenity: water.

The pending crisis has pushed the city to action, and public officials, businesses and households have turned to an innovative solution: The Sri M. Visvesvaraya Rain Water Harvesting Theme Park educates and informs Bangalore residents about issues surrounding water scarcity.

The park, an initiative of the Bangalore water utility, is a green oasis amidst dirt roads and concrete homes. There, groups of schoolchildren mix with architects, plumbers and contractors around 26 different models displaying water harvesting methods. The park itself also sets an example - not one drop of rain that reaches the park is wasted.

Rainwater harvesting in Bangalore (photo: Mark Bergen)
Vishwanath of the Rainwater Club says Bangalore needs multiple water sourcesImage: Mark Bergen

Running dry

The population of Bangalore - one of India's wealthiest cities - has increased by 7 million over the past 40 years. But only half of the Bangalore's current 8.3 million residents receive water from public utility pipes. The remainder rely upon groundwater - a source that has reduced in quantity and quality.

Access to potable water is a problem throughout India. Yet Bangalore is particularly high and dry - it rests 900 meters (almost 3,000 feet) above sea level and nearly 100 kilometers (62 miles) from the nearest large water source, the Kaveri River. Faulty infrastructure causes nearly half of the river water pumped from the Kaveri up to Bangalore to be lost, leaving the city short 300 million liters (almost 80 gallons) per day. And the shortage could worsen.

S. Vishwanath of the Rainwater Club said Bangalore will not only have to depend on the Kaveri, but should "also look at multiple other sources." Vishwanath serves as secretary general of the International Rainwater Catchment Systems Association, as well.

Also known as the "Zen Rainman," Vishwanath has been an ardent supporter of alternative water sources for several decades. In his own home, he harvests around 100 kiloliters (26,000 gallons) of water a year, capturing rainwater in plastic barrels. He points out that while the city receives about 1.5 billion liters (1,200 acre-feet) per day from the Kaveri, potential capture of rainfall could double that supply.

Heavy rain (AP Photo/Mark Baker)
Rain water harvesting is in fact obligatory for many larger buildingsImage: AP

That rain falls everywhere in the city is another major advantage, as this means anyone could harness its potential. "We don't need large storage systems to harvest rainwater," Vishwanath explained. "Even a small storage system can fill up and be emptied many times."

Proactive steps

Although rainwater harvesting won't be a cure-all for Bangalore's water shortage, it could be an important supplement. And the city government is finally catching on.

The Bangalore municipal government actually passed a rule requiring rainwater harvesting in 2004, but it was weakly enforced. In 2011, Bangalore's water utility implemented a policy making it compulsory for larger, existing apartment complexes and homes to incorporate rainwater harvesting. Those who don't abide risk having their water turned off.

In addition, a few tech parks - sprawling corporate campuses sprinkled across the city - are also starting to adopt rainwater harvesting systems. With their vast roof area, each building can collect up to 10 million liters (more than 8 acre-feet) of rainwater per year.

(photo: Mark Bergen)
Water harvesting is a cost effecitve method for the city's poorImage: Mark Bergen

In fact, after Chennai - the capital of neighboring state Tamil Nadu - Bangalore captures the most rainwater for reuse in all of India. And despite water infrastructure hurdles, the city has taken proactive steps that are unusual for a public agency in India.

"It's been very forceful and progressive, what the city has done," said Vishwanath, adding that around 50,000 homes now follow the mandate. "For poorer residents, who must pay much more for water if they are outside the public utility reach, harvesting is a worthwhile investment," he said.

Green future

Tejaswani, a project manager at the water park, explained how even poorer Bangalore residents seek out the park's services: "It is a cost-effective method for them." A rainwater harvesting system starts at 5,000 rupees (57 euros), and can run up to 50,000 rupees (570 euros). Most of the cost goes toward paying for the storage tank, Tejaswani explained.

At one end of the theme park, a small amphitheater hosts educational seminars for rainwater harvesting skeptics. Programs range from specific talks for building engineers, to a community theater for non-English speakers.

B.M. Manjunath, the park's assistant executive engineer, said that if a low-income family constructs a tank, they could harvest enough water to last them throughout the dry season. "For a family of four, 12,000 liters is enough for one month."

Vishwanath concluded that Bangalore could have a green future. "It's one of the first [cities] to have a water utility in place. It's a thinking city, it's a young city and there's no reason why it shouldn't be a leader for all water and sanitation good practices - for India at least."