How to Cut Carbon With Graywater Use

It all comes down to smart thinking: Save water, save the air, save the planet. 

As drought continues to burn through most of Western North America, the last thing a resident in those parts might think about is their toilet. But in a few years, the water in every home’s toilet bowls might be what people just bathed in.

Greyter Water exam featured

Consumers like the Greyter HOME Water Recycling System because it efficiently repurposes shower and bathtub runoff. Builders like it because it’s easy to install. And Greyter staff like it because it’s good for the world. Courtesy Greyter Water Systems

That may sound a bit bizarre, but to the team at Greyter Water Systems, it makes perfect sense. They note that one-third of all water used in the home goes down the drain, most of it via the bathroom. All of it begins as precious, drinkable H2O. What better place to start with conservation?

There’s also that greenhouse gas situation. Flushing a toilet and rising carbon dioxide emissions (CO2e) seem a few mountain ranges apart on the “we killed the world” scale. But generating the energy needed to send water into homes and other public places, as well as heating or cooling it, isn’t entirely earth-friendly, according to the U.S. Environmental Protection Agency (EPA). 

Greyter Water Bell pose

Company co-founder John Bell believes an ultra-efficient 99.9 percent filtration system—which cuts indoor H2O consumption by up to 25 percent—makes the water recycling unit an obvious choice. Courtesy Greyter Water Systems

Three percent of the nation’s energy is used to pump and treat water, a number that translates into 8 percent of CO2e for the year. “So, conserving water conserves energy,” the agency notes. “And that reduces greenhouse gas pollution.”

John Bell, Greyter Water Systems’ co-founder and vice president of business development for residential homes, has a very common-sense point of view: “It makes absolutely no sense to flush toilets with drinking water.”

Enter the Greyter HOME Water Recycling System, a stackable washer and dryer-sized unit that captures shower and bathtub runoff, then filters it to near-potable quality for use during toilet flushing. About two showers a day supplies enough gray water to handle the daily flushing actions of a family of four; overall household water consumption can be reduced by up to 25 percent, or about 9,000 gallons per year, according to Bell. 


During a drought period the thought of losing hundreds of gallons of water from everyday household functions takes on new urgency. But Greyter Water Systems’ first-of-its-kind residential water recycling unit can put that lost H2O back to use. Courtesy Oneillbro/IStock

Greyter HOME also detects leaks, which the EPA heartily endorses. The agency notes that a leaky toilet can waste up to 200 gallons of water per day. That translates into about 100 kilograms of CO2 generated daily, or about the same as the entire bathroom when everything is properly functioning, according to 

The system has proven very popular with new home builders and municipalities, especially those that strive to create water-efficient communities. Its small size and completely self-contained structure—filtration, chlorination, pumps, controls, and water storage are all inside the unit—make it a fast install for plumbers. Meanwhile, the water savings—and also a drop in the monthly electric bill—resonates well with consumers. 

Carbon Reduction Stats

3% of U.S. Energy The amount used to pump and treat water for homes and businesses

8% of Greenhouse Gases The amount created by the nation’s water treatment actions 

200 Gallons of Water The amount of fresh water a leaking toilet can waste in one day

There are a few obstacles. Some municipalities have complicated and restrictive greywater management ordinances. Water utilities are still learning how the technology works and what the full benefits are to them. And retrofitting an existing house with a current Greyter HOME unit is problematic at best.

Still, there’s a lot to be gained by everyone. The team at Greyter believes it all comes down to a basic philosophy: “Reused water is smart water,” the company notes. “Our mission is to work hand in hand with builders, developers, engineers, and architects, along with municipal officials, by providing out-of-the-box solutions that assist in the creation of water-efficient communities.” 

GBM 2021 Eco-LeadersGreyter is a 2021 Green Builder Media Eco-Leaders award winner. Download the 2021 Eco-Leaders issue to read profiles of other winners of this prestigious award.