• 07.13.12

For Clean Water, Just Add Clay and Silver

Put together all the high-tech solutions you want, but one water filtration company is using simple analog techniques to clean water in Africa, with amazing results.

Nearly a billion people lack access to clean drinking water. The problem is tackled in different ways around the globe, and in Ghana a social enterprise called Pure Home Water is busy deploying producing and deploying using a low-tech solution: ceramic pot filters. The filters are aimed at low-income households whose water supply is currently from an unimproved source–households that add up to about a million people, or 50% of people in northern Ghana.


The social enterprise has trained locals to be experts in the handling of the hardware and software aspects of the ceramic pot filter as well as how to successfully integrate this technology into their homes. To date, the the group has reached 100,000 people and has just received an order for 1,250 filters and 1,250 hand-washing stations known as Tippy Taps.

“People talk about mobile technology, about how cell phones are changing the developing world. What we’re working on is the bottom billion, the billion people around the world without safe water,” says Susan Murcott, a Senior Lecturer in MIT’s Department of Civil and Environmental Engineering who founded the enterprise. “They’re not going to be able to put fresh water through their cell phone.”

Murcott has worked in water for a long time. A former poet, she made a gigantic career change to become an environmental engineer, and then took her skills in the humanities to the developing world, fusing engineering and cultural understanding. In 2002, she worked with a team of Nepali partners and a former student, Tommy Ngai, to invent the Kanchan Arsenic Filter.

In Ghana, the problem with the water isn’t arsenic, but microbes. Existing filters didn’t remove microbes from muddy water; most of the water in Ghana isn’t the clearest you’ve ever seen. So Murcott’s ceramic pot filters do two things: they filter out the sediment, and they kill microbes using a coating of silver nanoparticles. The filters sieve about 10 liters of water per hour through their clay, removing 99.7% of bacteria and 92% of the turbidity, or muddiness.

The ceramic pots–produced in 36 factories in 18 countries from Cambodia to Nicaragua–are now being used around the world, says Murcott. She has been able to bring more than 100 MIT students to the small factory that produces the filters to help with the process. The filters cost only $5 to give to local residents, and the factory also employs local women to process the clay. Studies have shown that even without improved sanitation or other hygiene advances, safe water alone can reduce incidences of diarrheal and other enteric diseases by 6% to 50%.