Epic Cleantec is one of the winners of Fast Company’s 2023 World Changing Ideas Awards. Explore the full list of projects we’re honoring for making the world more equitable, accessible, and sustainable.

With much of the world suffering from lack of precipitation, you don’t have to live in Arizona to have become more cognizant of the water swirling down the drain or exiting the toilet. In this era of the megadrought, Epic Cleantec’s OneWater System allows buildings to recycle water on-site (a requirement that many cities are enacting on large buildings), lowering the amount of new water that needs to be drained from reservoirs. It’s the winner of Fast Company’s World Changing Ideas Award in the Water category.

Originally conceived as part of the Bill & Melinda Gates Foundation’s Reinvent the Toilet Challenge, the device uses a fine-mesh screen to filter out solids from liquids. The liquids are filtered and treated, and water is sent back into the building. By law, water treated on-site can be used only in non-potable applications, which can amount to 95% of a building’s water use: flushing toilets, irrigating plants, or filling cooling towers. The solids are taken off-site and turned into soil, which the company will donate to local parks departments and also make available for sale in bags.

OneWater System also uses heat from the roughly 80-degree wastewater to pre-warm new water, which comes into buildings at around 55 degrees. By transferring just a few degrees of heat, the process can reduce the amount of energy needed to heat water by 35% to 40%.

The company’s first project was in a 40-story high-rise in San Francisco in 2021, reusing up to 7,500 gallons of water per day from showers and laundry—2.5 million gallons per year from a single building. A modular version, launched in November 2022, is even easier to deploy. The company now has ongoing projects throughout the western U.S.

“We are doing for the water world what solar did for energy,” says Epic Cleantec cofounder and CEO Aaron Tartakovsky, “moving away from big giant energy plants to smaller, distributed even at home scale.”