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The Toilet of Tomorrow Will Do More Than Flush Waste

It will help modernize old or inadequate city sewage systems that harm public health—especially in developing countries.

A public toilet in Dhaka, Bangladesh. (Andrew Biraj / REUTERS)

When we think about the most dire threats to our planet, poor sanitation rarely tops the list. And yet it’s a significant (and in some cases immediate) contributor to sickness and pollution in both rural and urban areas.

Every day, around 2 million tons of human waste are disposed of in water channels. Among other contributing factors, this sanitation problem limits the availability of uncontaminated drinking water—especially in developing nations, which often lack the proper treatment and drainage facilities. Overall, 2.5 billion people around the world currently lack access to improved sanitation, and 27 percent of urban dwellers in developing nations do not have access to piped water in their homes.

These sanitation issues apply to U.S. cities as well—albeit on a much smaller scale. As America’s urban populations continue to grow, so too does the demand for clean water. The U.S. Government Accountability Office reports that 40 states will experience some kind of water shortage in the next 10 years.

These shortages negatively impact water quality in unincorporated communities, as my colleague Laura Bliss has chronicled in her series on the water crisis in California’s San Joaquin Valley. Meanwhile, urbanized areas run the risk of sewer systems clogging and spilling over into rivers and streams due to excessive groundwater or stormwater. The EPA estimates anywhere from 23,000 to 75,000 overflows of sanitary sewer systems each year in the U.S.

The right infrastructure becomes critical in preserving water quality and preventing a shortage of clean drinking water. Unfortunately, most of the technology employed by cities today lags behind the latest innovations.

Reinventing the toilet

Currently, only one gold standard for sanitation exists: the combined sewer system that is already in place in developed cities. In a September post for The Atlantic, author Mary Anna Evans describes the initial design of this “modern” technology:

The EPA calls combined sewers “remnants of the country's early infrastructure.” The first sewers weren’t designed to handle the constant and huge stream of wastes from our toilets, because they were invented when we didn’t have any toilets. Sewers were originally built to solve the problems of cities that were flooded with their own refuse—garbage, animal manure, and human waste left in the open rather than in a privy or latrine—during every rainstorm.

The fact that cities still rely on a technology that predates toilets points to just how archaic this system has become. Brian Arbogast, the director of the Water, Sanitation & Hygiene Program at the Bill and Melinda Gates Foundation, says that “there’s not an obvious market demand for changing the way we do sanitation in the developed world.” And yet combined sewer systems expend huge amounts of water and energy, in turn posing a serious long-term threat to our environment.

For the past few years, Arbogast and his team have worked with partners to develop new sanitation technologies. One of the most promising is a “reinvented toilet” that essentially functions as its own treatment plant. The concept is part of a broader initiative called the “Reinvent the Toilet Challenge” that aims to deliver sustainable sanitation to the 2.5 billion people who lack access.

Unlike traditional sewer systems, the reinvented toilet would harvest energy from actual human waste to kill germs in the water itself. The result is sterile water that’s safe enough to wash with, as well as human waste that can be re-purposed for healthy, odorless fertilizer. The main challenge is keeping costs low enough to reasonably implement the toilet across cities. With this in mind, the Water, Sanitation & Hygiene Program has priced it at no more than five cents per user per day—the same cost as many public toilets in developing nations.

The Gates Foundation has also partnered with manufacturing company Janicki Bioenergy on a device called the Omni Processor, which is able to convert feces into safe drinking water. The device’s steam engine makes its own energy for burning human waste so cities or towns don’t have to resort to energy-draining activities like burning diesel fuel. The Omni Processor was recently implemented in Dakar, Senegal, through an auspicious pilot program, with plans to eventually sell the product to wealthier nations.

Developing cities as sanitation testing grounds

If developing nations are turning toward new sanitation technology, why isn’t this shift happening in developed cities as well? One obvious explanation is that developed cities already have a functioning sewer system. But the real answer, Arbogast says, goes beyond the fact that “developed cities aren’t really innovating.” He contends that new technology will have to be tested in developing nations before developed ones are likely to follow suit.

“I firmly believe,” he says, “that if this technology can get out there in the market [in developing countries] … you’ll start to see building codes changing to incentivize the use of waterless toilets or to take the load off waste water treatment plants.”

Until then, it’s developing cities that require the most attention. The World Health Organization reports that 3.4 million people—mainly children—die each year from water-related diseases like cholera, dysentery, or typhoid. In a city like Dhaka, Bangladesh, Arbogast says, only 2 percent of waste is being treated at a plant. And in many cases, septic tanks carry human waste directly into the street—leaving city residents exposed to numerous pathogens. “No community has ever put themselves out of poverty without addressing sanitation,” Arbogast says.

As dire as these circumstances may be, sustainable sanitation is rarely the focus of global discussions. During COP21, Arbogast gave a talk on the relationship between sanitation and climate change in hopes of landing the issue on the international radar. At the conference, Arbogast says, many were surprised to hear how direct and devastating the link has become. Despite being familiar with the sanitation problem in developing communities, many conference-goers had overlooked the energy-draining and water-depleting activities of combined sewer systems.

Thankfully, these realizations are not too late. With innovations like the Omni Processor and the reinvented toilet on the cusp of completion, cities can start to think about replacing sewer systems with more environmentally friendly devices. Arbogast thinks these technologies will be ready for purchase in just a few years. Developed or not, those cities that make it a priority to update their waste disposal systems will certainly be more prepared for impending environmental challenges.

“Cities that invest in non-sewer sanitation are going to be far more resilient both today,” Arbogast says, “and even more so in the face of climate change in the future.”

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