greywater systems

Would You Reuse Household Waste Water? The Do’s and Don’ts of Greywater Systems

Hundreds of thousands of gallons of water literally go down the drain each year from your household appliances. In fact, an average family of four uses 400 gallons every day, according to the Environmental Protection Agency (EPA).

You may have already tackled ways to pare your water use—from basic tasks like fixing a leaky toilet or sprinkler head to turning off a faucet when brushing teeth or washing dishes. But there’s another alternative: reusing your household waste water.

Droughts spur interest

As water becomes increasingly precious–and expensive–and more areas of the country are facing droughts, there seems to be increasing interest in water systems that repurpose greywater (the generic term for water from showers, bathtubs, laundry and bathroom sinks ) in your home.

These greywater systems carry used water away from household appliances and clean it for use in irrigation (and, sometimes, for indoor plumbing uses like flushing toilets).

Greywater /noun/ Household wastewater (as from a sink or bath) that does not contain serious contaminants (as from toilets or diapers).

Nationally, outdoor water use accounts for 30 percent of household use, according to the EPA. And those numbers can skew higher, depending on the climate.

In Southern California, for instance, the Department of Water and Power calculates that irrigation represents 60 percent of water use for an average home, says Buzz Boettcher, managing member of Water Recycling Systems in Redondo Beach, Calif., a company that designs, builds, and installs water reuse systems.

From laundry to landscape

So, how does a greywater system work? Boettcher says that used water is carried away from household appliances and sent via underground piping to a processor on your property for cleaning. There, the water is filtered, disinfected, pressurized, and sent into drip irrigation pipes to be held for a set period and then released to water lawns, trees, shrubs, flowers, or to wash cars and hose down hardscape.

Water from toilets, garbage disposals, and dishwashers (what’s known as “blackwater”) can’t be treated safely for reuse and instead must be sent separately to a sewer, he explains.

The greywater concept is still relatively new, and not all municipalities permit these systems to be installed in a residential setting, says Boettcher.

Greywater ROI

The biggest downside? It can be pricey—about $15,000 to purchase and install a complex system that distributes water to multiple zones or stores water for later use, Boettcher says. Flotender, a Seattle-based company, has similar pricing for multi-zoned systems, says company representative Justin Berkey. Both companies sell less expensive single-zone, or irrigation-only, systems.

How quickly costs are recouped depends on an area’s water fees, plus surcharges for sewage disposal, says Boettcher. Generally, a family of four with teenagers who might take long showers frequently could expect a payback within four to six years, he says.

There may also be incentives in place to help with costs. For instance, the state of Arizona allows one-time tax credit of 25 percent of the cost of a greywater system (up to a maximum of $1,000).

Despite the significant outlay of funds, some homeowners may be more eager for the possibility: those who live in an area with a water shortage, whose community ordinances restrict irrigating yards, who purchase a new home in a city that requires it to be equipped from the get-go with this feature, as Tucson, Ariz., does; or those who simply want to be good eco-citizens.

Greywater guidelines

Here’s what else you should know:

  • Find out if your community permits a greywater system (some don’t); ask your water or health department. Even if you get a “no,” some suppliers will work with you to obtain permits, says Boettcher.
  • Find out if your state or municipality offers a tax credit or a rebate; Tucson, for instance, provides a cash rebate for greywater system installations.
  • Ask how finely a system filters debris; get a number and compare it to others.
  • Make sure the system is compatible with irrigation equipment you already have, so you don’t have to replace it.
  • Ensure that any new unit will be accessible for cleaning and replacing components.
  • Buy a system with sensors that detect freezing temperatures, so you can turn it off or so it turns itself off automatically.
  • Make sure there’s an overflow device to divert greywater to a sewer in case of problems, such as significant rains.
  • Consider buying a warranty along with your system. 

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