On a stage in Beijing, Bill Gates took out a beaker of yellowish-brown fluid and put it on a nearby podium.

“This is a container of human waste,” he said, as a colorful animation of the teeming multitudes of viruses commonly found in poop cavorted on a screen behind him. “This, we’re going to keep in the jar.”

Gates was speaking at the opening of the three-day Reinvented Toilet Expo in China, which is showcasing the different toilets and waste-processing concepts that have resulted from a 2011 Bill and Melinda Gates Foundation challenge to change what happens to the poop of billions of people. In large swathes of the world, waste is often left untreated, contaminating sources of drinking water, and spreading diseases that cause childhood deaths, malnutrition, and developmental delays.

Bill Gates talks toilets in China.

It’s no easy feat bringing about such a revolution.

Some 175 years ago, the world’s foremost cities began to change on a massive scale how human beings went to the bathroom. In the second-half of the 19th century, London set up a municipal works office to lay a vast underground sewerage network that would end the use of the Thames River as a dump for human waste (or what was known as the “Great Stink“) and the recurring cholera epidemics that resulted from poor waste management. Baron Haussman modernized Paris’s sanitation system around the same time.

But the heavily populated cities of emerging economies couldn’t afford to replicate those works. In India’s two most populous cities, an estimated 25% of sewage flows untreated to streams or the sea in Mumbai; while in Delhi, where the last toilet expo took place, more than 50% of sewage is untreated. China’s president launched a “revolution” to improve toilets at tourist sites and in rural areas in 2015, with 40% of people at the time still lacking access to safe sanitation. Meanwhile, South Africa’s rundown sewage system is collapsing due in large part to mismanagement at wastewater plants.

Recognizing these challenges, the Gates Foundation in 2011 offered grants to get scientists and businesses to take a different approach, by inventing toilets that would be cheap to build and use, could consistently get rid of pathogens, would work without being connected to a large system to deal with the waste, and could be widely adopted.

According to Gates, that technology is now ready to market. What this generation of toilets needs now is someone to popularize them. What they need is their very own Thomas Crapper.

A brief history of the flush toilet’s spread

Various men are credited with inventing the flush toilet at various times, from John Harington, a godson of Elizabeth I, in the late 16th century; to Alexander Cummings, who in 1775 got a patent for a flush toilet invention; to Ismail al-Jazari, a 13th-century inventor with an early interest in automation. What Thomas Crapper, a Victorian plumber, brought to the process was not novelty, but marketing.

While he’s often wrongly credited with inventing the flush toilet, Crapper—yes, that really was his name—was important to its adoption as the man who first marketed sanitary fittings in a big way. As a teenager, Crapper had apprenticed as a plumber, and built his own plumbing business a decade later. In 1866 he opened a bathroom showroom in London’s Chelsea neighborhood. The showroom made it possible to test (and even try out) different kinds of toilets, which made people more receptive to the idea of actually putting these in their own homes. (Of course, while the flush toilet was an improvement in personal convenience, its adoption may have made the Thames dirtier until the sewage system was improved.)

The history of toilets on display at the Plumbing Museum in Watertown, Mass.
Image: Reuters.

Water-free flushing and the “omni-processor”

The Gates Foundation believes the new plumbing technologies might be as cost-effective as existing options already in multi-unit situations, like schools and tourist areas, with the potential to become a $6 billion market in the next decade. “It’s not competitive for a single-unit today,” Rodger Voorhies, head of the foundation’s global growth division, which covers sanitation, said. “In the long run it will get cheaper and more efficient.” For the foundation, China is both a market for these new toilets, and a place that could help produce them cheaply.

The offerings at the expo, Voorhies noted, run the gamut from toilets with biological and chemical processes to membranes that filter liquids, like one model from the UK’s Cranfield University designed for a household of up to 10 users (see featured image). Their toilet looks like a regular one. but its pedestal houses a self-contained treatment system that uses no water or power. Solids are extracted, dried and combusted in the pedestal, which produces ash that has to occasionally be thrown out. A model from Swiss company Helbling appears to operate in some way similar to a French press, separating liquids and solids, and using high temperatures to treat the solids.

The Janicki Omni-Processor, developed by Washington-based Sedron Technologies, is being piloted at a wastewater treatment plantin Dakar, Senegal, in partnership with the country’s National Office of Sanitation. (Omni-Processor is a somewhat technocratic word coined by the Gates Foundation to refer to the fact that the treatment machines can handle more than just human waste.) The machine dries out wet solids and expels some of it as ash. Sludge steam goes through a filter and goes on to produce potable water (which Gates has sampled himself) while water products that aren’t potable are used to generate electricity.

The first commercial version, which is expected to ship to Senegal in 2019, should be able to handle waste from at least 100,000 people and is expected to cost $3 million to $4 million. Sedron hopes that all of Dakar’s waste can eventually be treated by plants and operators running Omni-Processors.

Voorhies hopes that these toilets will one day mimic the way mobile phones allowed people in emerging economies to skip over landlines. In his remarks Tuesday, Gates referred to his history as Microsoft co-founder in overhauling personal computing, at one point comparing solving the world’s sanitation problems to “a major new version of Windows” then adding it would go beyond even “what a very cool piece of software can do.”

Given our current obsession with technology it’s not surprising we increasingly turn to the sector for metaphors to talk about change in any context—but talk of disruptive toilets may be a little too much for some to digest.

Toilet paper… or water?

The issue of how to enable more people to go to the bathroom safely and with dignity is only in part a problem of infrastructure and technical design. As with all complex social problems, solutions need to be psychological and cultural as well. Otherwise the efforts to reinvent the toilet will be scuttled by locally-shaped, personal preferences.

These preferences depend upon whether your home is surrounded by forest or in arid desert, whether you think your business should be followed with toilet paper or water, whether you follow a disciplined morning ritual or are more free-range in your habits, differing privacy needs depending on attitudes about women and menstruation, and ideas shaped by religion and other mores about what’s dirty, and what’s clean.

Another major part of changing toilet use is what comes after you put in place a nice, new facility. Who will keep it up and ensure it’s used by the community?

The foundation says that user behavior and perceptions are part of what businesses will have to address to popularize these toilets. In other words, now that scientists have done their work, it’s time for modern-day Thomas Crappers to step up.