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Safe at the source

Stanford researchers are developing an affordable and sustainable solution to the challenge of providing safe drinking water to nearly 1 billion people in city slums around the world.

For many of the nearly 1 billion people living in the world's urban slums, finding a safe water supply is impossible. A team of Stanford researchers led by Jenna Davis, the Higgins-Magid Senior Fellow at the Stanford Woods Institute for the Environment, is working to change that with a low-cost chlorination device. Unlike decades' worth of proposed solutions before it, the device would disinfect water at the point of collection, and require no behavior change from users.

Davis and other members of the Lotus Water project – a joint effort led by the Stanford Woods Institute's Program on Water, Health and Development – envision a device that has no moving parts, requires no electricity and would sell for $20 or less. "This makes it sustainable and scalable in low- and middle-income countries," said Davis, an associate professor of civil and environmental engineering.

Kurt Hickman

750 million people lack access to safe drinking water

Once attached to a pump, the device doses water with a precise amount of chlorine each time the pump is used. The chlorine residual would last about a week, long enough to protect against recontamination during transport and storage.

This novel approach overcomes the challenges and high costs of city-wide water treatment, while removing the burden of having to treat water in people's homes.

The issue could not be more pressing: globally, diarrhea caused by waterborne pathogens is the second leading killer of children younger than 5, according to the World Health Organization. Lotus Water co-adviser Stephen Luby, a professor of medicine, helped kickstart the project because of his interest in water's contribution to health. "I've worked on water and health issues for more than 20 years," said Luby, a senior fellow at the Stanford Woods Institute and the Freeman Spogli Institute for International Studies. "Most of those efforts asked people to treat water in their own homes. This project is radically different."

“For many [urban slum residents], finding a safe water source is impossible.”

The Lotus Water Project's service model relies on monthly payments from landlords, who typically own shared water points in Dhaka, Bangladesh, one of the world's most densely populated cities. The team's research indicates that slum residents are willing to pay higher rents in exchange for higher-quality water. Linking the device's lease to service payments would hold landlords accountable to their tenants. "They have an incentive to improve their tenants' quality of life," said Amy Pickering, an engineering research associate with the Program on Water, Health and Development. On average, a 1- to 2-percent rent increase would be sufficient to cover device maintenance, according to Pickering.

When they've perfected the chlorinator – which they hope to do by the end of 2015 – the researchers plan to install more than 150 devices that will serve about 10,000 people. The team continues to refine its design while considering other similar devices, evaluating health impacts of access to chlorinated water amid other health hazards present in the slums, and testing the viability of potential business models such as different packages of chlorine refill and hand pump maintenance services.

Other partners in the Lotus Water Project include: International Center for Diarrhoeal Disease Research, Bangladesh; Dhaka University; Dustha Shasthya Kendra; Dhaka Water and Sewerage Authority; and Medentech.

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