This week Bill Gates announced the winners of his foundation's Reinvent the Toilet Challenge and the top prize went to a solar-powered toilet that produces hydrogen and electricity. The goal of the contest is to invent a toilet that doesn't use water or a sewage system for places in the world that lack those resources. Toilets that use much less water are a priority in this country and in Consumer Reports latest toilet tests we gave top scores to five water misers.
By federal law, all toilets made since 1995 must use no more than 1.6 gallons per flush. Toilets that meet the Environmental Protection Agency's WaterSense requirements use just 1.28 gallons per flush or less, on average. Using less water needn't mean less flushing power: Of the 11 toilets that made our latest winner's list, five are WaterSense models that use 1.28 gallons per flush, yet performed comparably in our tough, solid-waste tests to top-scoring toilets that use 1.4 to 1.6 gallons per flush.
When Consumer Reports tests toilets it uses a mixture of baby wipes, sponges, plastic balls, and tubes to simulate solid waste. For liquid waste, we use water colored dark-blue. But because the toilets in the Gates competition cannot rely on water, they were tested with fake feces made from a mixture of soybean paste with a bit of rice mixed in. "You need to demonstrate what the equipment can do without having the real stuff around," Carl Hensman, who leads the water, sanitation and hygiene programs at the Gates Foundation, told NPR.
The WaterSense toilets that earned top marks at Consumer Reports were made by American Standard, Aquasource, Kohler, Toto and Glacier Bay. Placing second and third in the Gates competition were a toilet that uses energy from solid waste to decompose it and recover clean water, and a model that sanitizes waste within 24 hours through dehydration and smoldering. (You can find photos on the Gates website.) The foundation's goal is to place models of the winning toilet in a community by the end of 2014 or 2015. But if you want to do your part to conserve the world's resources, you can buy a water-saving toilet now.
—Mary H.J. Farrell