Bill Gates is not a squeamish man. He also has an abiding faith in technology. And so it is that the former head of Microsoft Corp., now co-chair of the Bill & Melinda Gates Foundation, has turned his attention to the reinvention of the toilet.

As Gates knows, two-thirds of the world's people have no access to that great leap in sanitation, credited with adding a decade to our longevity. Their communities can't afford the water and sewerage systems to which the toilet must be attached. So they make do with latrines or squat in the open, and consequently suffer diarrheal diseases that kill two million annually.

Gates intends to change that. The Gates Foundation yesterday announced three winners from eight projects it funded to develop low-cost, water-less toilets. The California Institute of Technology won first prize for a device that includes a solar-powered electrochemical reactor that disinfects waste and generates hydrogen to be used as fuel. The model from the U.K.'s Loughborough University generates clean water from urine and feces and uses a hydrothermal carbonization reactor to turn solid waste into biological charcoal that can be used as fertilizer. The University of Toronto entry dries and smolders waste to sanitize it and uses a sand filter and ultra-violet light to recover clean water.

The foundation will determine whether one, two or all three of these prototypes are viable and will field test them before initiating pilot studies in the developing world in about 2015. The goal is to develop a toilet that can be operated for no more than 5 cents per day per user.

That's an ambitious goal, but it's the right one. If the new toilets aren't affordable, they won't be adopted. The foundation's model assumes that, rather than governments or donors buying the devices and imposing them on users, the private sector will deliver them to interested consumers and that commerce will flourish around the collection of waste-turned-to-resources.

At the awards ceremony, Gates noted that the toilet has changed so little in 200 years, today's versions would be familiar to Thomas Crapper, who popularized the flush variety in the late 1800s. With the innovations the foundation's grants are generating and a free-market model, Crapper's ghost may yet be surprised.

(Lisa Beyer is a member of the Bloomberg View editorial board.)

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