What is greywater and how can it be used?

Plants irrigated using greywater. | Photo by Laura Allen

Your homestead may be beautifully landscaped for spring, but odds are, you are using a fair amount of water to keep it that way. If you want to be more sustainable with your water use on your homestead, one way is by reusing greywater.

Greywater is the used water from your bathroom sinks, showers, tubs and washing machines that may have come in contact with soap, dirt, food, grease and hair, but has not come into contact with feces (this is known as “blackwater”).

While greywater may look cloudy and slightly dirty, it is a safe and even beneficial source of irrigation water in a yard.

“It doesn’t make sense to use potable water to irrigate flowers, trees, bushes and things like that,” said Remy Sabiani, owner of the Water Wise Group, the leading distributor of greywater systems based in Templeton, California. “You can basically reuse the water coming from the shower, the bathroom, the sink or the laundry. [If you are on city water,] you pay once and you use it twice.”

According to the United States Geological Survey, the average American uses between 80 and 100 gallons of water every day, as much as 60 percent of which can be used for outdoor irrigation. Estimates vary based on location, but on average, it is estimated that the average 40 gallons of that daily water use results in greywater.

“Reusing greywater makes ecological sense,” Laura Allen, co-founder of Greywater Action. “Keeping water to drinking standards that takes a lot of energy and cost. If we can reuse that water, we can save on that.”

Using greywater in your yard can benefit surrounding ecosystems as well. The nitrogen and phosphorous in greywater can pollute rivers, lakes and estuaries, but for the plants in your yard, it is valuable fertilizer. Reusing your greywater also keeps it out of the sewer or septic system and reduces the chance that it will pollute local water bodies.

Is using greywater legal?

In many Western states that are more drought-prone, reusing greywater is legal. Regulations in the East Coast and Midwest are spottier.

“There is a risk associated with greywater, it’s much easier [for regulators] to say no than to say yes to something that they’re not familiar with,” Allen said, noting that there have been no cases of illness associated with the use of greywater in the United States. “It’s a mental shift and a change in how we’ve been looking at water for a long time. When you live in a state that has water scarcity or drought it’s easier to convince people to try something different.”

Greywater Action maintains a map of the states where greywater reuse is legal, as well as some of the codes for specific state.

“Some states don’t allow greywater at all,” Allen said. “For others, you have to follow a few guidelines.”

According to Greywater Action, greywater reuse is legal in Maine, though only for residential irrigation. Maine has restrictions on the number of organisms that can be in the water as part of its irrigation water quality requirements, so disinfection is usually required to use greywater for irrigation, as well as a permit.

“Any proposed discharge to the ground or a water body, including the external reuse of grey water [sic], requires a discharge permit as appropriate from the Maine Department of Environmental Protection,” commented Emily Spencer, acting director of communications for the Maine Center for Disease Control and Prevention. “Absent a permit, disposal in an appropriate septic system or sewer once any wastewater has been discharged from a structure is always required.”

How to reuse greywater

If you aim to recycle greywater for irrigation, you must use plant-friendly products, or those without lots of salt, boron or chlorine bleach that can damage plants.

“The quality of irrigation water will depend on what people put in the water,” Allen said. “To successfully use greywater, it’s important to have a little education about plant-friendly products.”

The easiest way to use greywater is to pipe it directly outside and use it to water ornamental plants or fruit trees. Greywater can also be used to irrigate vegetable plants as long as it doesn’t touch edible parts of the plants.

“You can water anything that likes to be irrigated, but the greywater shouldn’t touch the portion of the plant that you eat,” Allen said. While root vegetables are a no-go, trees and any other plants with food above the ground are suitable for greywater irrigation, as there is no direct contact between what you plan to ingest and the non-potable water.

The easiest way to start reusing greywater is to hire a plumber to set up an automatic irrigation system in your yard.

“That way, when you’re doing laundry, you are also watering your trees,” Allen said with a laugh.

There are some DIY approaches you could take as well.

“There are some really simple systems that work really well that are totally doable for the average person that’s handy and works around their home,” Allen said. She’s the author of “Greywater, Green Landscape,” a book that could get you started.

Greywater reuse system. | Photo by Laura Allen

These DIY systems tend to be less efficient than their automatic counterparts, though.

“I read stories about people in the sixties or seventies [who] would use catchment, but that’s not convenient, nobody has that time,” Sabiani said. “There are people who do it themselves with some filters, but it will never be automatic and it will fail most of the time. You could do it yourself, but it is best to work with a plumber for your installation.”

Greywater can also be reused in your toilets, with some stipulations.

“Toilet flushing is really challenging to do right,” Allen said. “If you put greywater in the tank of your toilet, even if you filter it, it’s got grime and if it sits around in the toilet tank, it can get smelly and cause leaks.” Allen said you can pour greywater directly into the toilet bowl for a “bucket flush,” though.

Setting up a system to reuse greywater around your homestead will not only save water and money on your bills, but it may help you feel closer to the resources around you.

“For me, it’s kind of this exciting, empowering thing,” Allen said. “Why are we wasting all this water that we’re using every day when we can easily reuse it?”

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