Pre-1990s toilets practically flush money down the drain, using 3.5 gallons or more with each flush.
Even newer low-flow toilets still demand 1.6 gallons of fresh, potable water every time, and standard urinals aren’t much better at 1 gallon.
But a growing trend, reusing so-called graywater, could dramatically slash a building’s water bills, according to Jason Rector, owner of water conservation manufacturer and dealer AquaPro.
With a few modifications to the plumbing system, you can recycle the building’s graywater – the used water from showers, washing machines, and bathroom sinks that’s not drinkable, but generally harmless when treated properly – and use it to flush toilets or irrigate the surrounding landscape instead of using precious potable water.
In commercial applications, Rector says, the potential savings are significant, depending on local water prices and how drought-prone the area is.
"You’re not only saving money, you’re saving the resource," Rector says. "Estimates are that anywhere from 40 to 60% of water in buildings is being flushed down the toilet."
Different Strokes for Different Facilities
Dorms, hotels, and other facilities with individual one-toilet, one-sink bathrooms would find simple, point-of-use graywater systems to fit best. Such units collect water from one bathroom sink, filter it, and redirect it into the tank of one nearby toilet. These can cost about $300 per unit, Rector says.
A commercial product can handle the volume in bigger buildings, where a row of stalls accommodates several people at once. A reservoir under the ground holds graywater as it’s generated, then parcels it out with lift stations and pumps whenever a flush is needed. In the meantime, filters remove lint, hair, and other particles, and chlorine disinfects it. This type of setup can cost $40,000 to $70,000 after all needed accessories are factored in, Rector says.
Dual-flush toilets, waterless urinals, and other devices add to the cost savings. But to Steve Sheldon, the architect and developer for Ibis Builds, water management practices like these aren’t just cost-effective – they’re a moral issue too. Under his leadership, Florence Lofts, a mixed-use development in Sebastopol, CA, became the first large-scale graywater system in Sonoma County.
Florence features a 4,000-square-foot commercial building with retail and office space, plus 12 two-story "live-work" units, where the tenants commute to the office or studio by walking down the stairs. The lofts combine graywater technology with permeable pavement, low-water fixtures, and other sustainable practices. For this reason, the development earned LEED Gold certification.
Graywater recycling isn’t used in Florence Lofts’ commercial building because California law prohibits this, Sheldon says, but the lessons he learned creating the community are applicable across the board. The landscape surrounding the lofts is irrigated by a subsurface graywater system, and the plants seem to grow faster than Sheldon first expected. He attributes this to the extra dirt and biological material that ends up in the graywater whenever tenants wash their hands or clothes.
"The question is, how valuable is it to save water?" Sheldon asks. "The cost that we face in terms of dollars and cents in the moment doesn’t really take into consideration the bigger cost involved."
Flushing in the Future
Since Sheldon conceived of Florence Lofts’ system five years ago, graywater’s acceptance nationwide is booming. More local jurisdictions now permit graywater recycling as long as no one comes into contact with the water, Rector says.
"It’s going to become a lot more common practice in new construction," Rector adds. "Apartments and hotels are the ones who are really looking at ‘how can we retrofit to save money,’ because they’re huge water consumers."
This development represents the changing tide in building management, Rector says. Graywater has become a real conservation option for commercial and residential buildings alike.
"We’ve flushed clean water down the toilet for 100 years now," Rector says. "You don’t have to use clean water to flush the toilet."
Janelle Penny (firstname.lastname@example.org) is associate editor of BUILDINGS.