Irrigating With Graywater
Water. It’s vital to all life. Humans, plants and animals can’t live without it. But the problem is, it’s getting scarcer. And, in many places, more and more expensive.
One way to deal with scarce or expensive resources is to use less of them. To save on gasoline, we buy fuel-efficient automobiles. By now, most of us are used to separating our trash and recycling our cans, bottles and paper. We’ve all learned the mantra: reduce, reuse, recycle.
Fortunately, water is one of those resources that can be recycled. When it’s reclaimed from the laundry, bath or shower—and sometimes, the kitchen sink—it’s called graywater.
Using graywater to irrigate landscapes is a growing trend across the country, especially in arid states like Arizona, California, New Mexico and Texas.
Aside from that, “nothing about graywater is simple,” says ecological designer and graywater expert Art Ludwig. “Every answer has asterisks around it.”
Ludwig consults internationally on the design of water, wastewater and solar energy systems.
He’s also a designer of graywater systems and the owner of Santa Barbara, California-based Oasis Design. He’s been intimately involved with graywater for 33 years.
Check your local ordinances
With graywater, we need all the information we can get, because the water isn’t all that’s murky when it comes to the legality of graywater systems. “The majority of the country has no regulations,” said Los Angeles-based graywater activist Laura Allen.
“That means if you want to do it legally, you’ll have to reinvent the wheel with your local agency. You’ll need a permit, because you’ll be deviating from building and plumbing codes.” According to the EPA, “Only about 30 of the 50 states have regulations pertaining to the recycling of graywater.”
Ever dropped a mercury thermometer and found yourself trying to corral the dozens of little silver balls rolling every which way? If you have, you’ve some idea of what it’s like keeping up with graywater regulations around the country. It’s a hodgepodge, but you don’t have to know what’s legal in every state, just your own.
As this statement from the Environmental Research Foundation’s website puts it, “In many ways, regulations struggle to keep up with what is technically possible and theoretically needed. In the absence of water reuse regulations, the California Title 22 Code has become the de facto standard for water re-use.”
Some pioneers just forged ahead, and waited for the law to catch up with them. Allen’s involvement with graywater started one day in 1999 when she and her Oakland, California housemates got a very high water bill. “With very limited information, we created a system to send our shower water out to our landscape. The codes made it pretty much illegal, so I started an organization called the ‘Graywater Guerillas.’” Everything the Guerillas did was not up to the plumbing code, because, according to Allen, “it wasn’t legal to do this in California.” The group worked hard on getting the state code changed. In 2009, it finally did. “Now, everything we do is legal and much easier for professionals to incorporate.” (The Guerillas evolved into Graywater Action, which focuses on education, and The Graywater Alliance, which concentrates on policy. Both are based in Oakland. Allen is active in both groups.)
“Graywater prohibition didn’t stop homeowners from putting in systems, but it does stop the professionals,” said Ludwig. “Someone with a license doesn’t want to put in something that isn’t permittable.”
Don’t put your irrigation or business license in jeopardy. Before you install any kind of graywater system, it’s imperative that you check your local municipal and state ordinances, and keep on top of them.
They’re bound to change.
Everything but the kitchen sink?
Graywater is defined differently in different places. Arizona, for instance, allows graywater systems to recycle water from washing machines, bathroom sinks, showers and tubs. Kitchen sink water is considered “dark graywater,” and can be permitted, but only if the property is on a septic system and has a legally permitted composting toilet. (Toilet effluent is considered “black water” and is never allowed to be recycled to landscape.)
“It’s a regulatory loophole that was designed for off-the-grid residents out in the rural areas, to reduce their input into septic systems,” said Catlow Shipek, senior program manager and cofounder of the Watershed Management Group (WMG), a nonprofit organization in Tucson, Arizona. One of its missions is to help communities “manage the natural resources within their watershed.”
WMG puts on demonstrations and workshops on how to build and install graywater systems for the public and professionals alike.
Eric Mytko describes himself as “a landscape contractor who isn’t afraid of graywater.” He’s the founder of Life’s a Garden, a full-service design/build landscape company in Phoenix, Arizona. His company also installs conventional irrigation systems.
For now, he’s chosen not to include the kitchen sink in his graywater installations. “You can do what’s called a ‘kitchen resource drain,’ but that involves a lot more, so we just stay out of it for right now.”
The “lot more” is dealing with particulate matter. Naturally, there’s more of it with kitchen sink water than bathwater. But Mytko sometimes finds kitchen sinks hooked up after the fact to systems he’s installed. When asked if these were do-it-yourself jobs, he says, “We don’t know. We discover it when we get called out to find out why the pumps on our system are clogged.”
For a kitchen resource drain, Mytko “strongly recommends” a double-sink/double-hookup system, with one sink’s outflow going to the graywater system, and the one with the garbage disposal to the sewer. But first, check to see if kitchen sink graywater is legal in your area.
Not for lawns?
The vast majority of landscape water goes toward keeping turf alive. You would think that this would be graywater’s main application. That depends on whether you’re talking about commercial or residential applications. Graywater has been used for years to irrigate golf courses. But using graywater to irrigate residential lawns, “It’s the Holy Grail,” says Ludwig. “It gets tricky.”
According to Ludwig, there’s “a lot of push” in the residential turf direction. However, he wouldn’t sell anyone a graywater-to-lawn irrigation system today without letting them know that “at this stage they’re kind of experimental. The emitters can clog (from particulate matter). And the cost/benefit ratio may not pencil out that great.” However, he concedes that “if someone is on a marginal or failing septic system, it could be the best investment they could ever make.”
You may have noticed the “tricky” part coming in when he said “emitters.” Graywater-to-lawn always means subsurface drip. Because when we’re talking about graywater, we’re never talking about spraying it through sprinklers. Where regulations do exist, they never permit that. Ever. It’s not considered safe.
“It’s poor form to build in a pathway for transmission of disease into your system,” says Ludwig, “even though the levels of pathogens for graywater are so much lower than in combined sewage that they’re really not comparable as materials.” Even so, with sprinkler delivery, droplets become aerosols, with particles floating in air.
Ludwig uses the example of a person with a communicable disease having just taken a bath. When we take a bath, we shed skin cells, among other things, including small amounts of excreta. All of that carries pathogens into the graywater.
Then out it comes, through the irrigation system. “Now, picture kids at a birthday party running back and forth through sprinklers, breathing this stuff deep into their lungs.” Even though there’s never been a single documented case of graywater-transmitted illness in the entire U.S., according to Ludwig, “I would never recommend building a system that has that potential.”
Ideal for commercial settings
The water savings for a residential application can be substantial. That savings grows exponentially when we look at the commercial arena. “For a commercial, industrial, or institutional client, (graywater) is a definite yes,” says Ludwig. There, the cost/benefit ratio for grounds and several acres of playing graywater-to-turf is favorable. fields. You can see that there will be The difference, Ludwig explains, is a very quick payback time in water volume. Imagine a large institution, savings. “Going from, say, a $100 per such as a college, putting out thousands of gallons of water a day from means that an institution can spend day water bill to a $12 a month bill locker rooms and dormitories. Then $10,000 to $20,000 on water treatment equipment and still save add banks of washing machines, plus the irrigation of the campus money. With the treatment system, they can get that water clean enough so that it will not clog a subsurface drip system.”
But what about the plants?
Advocates all say that plants thrive in graywater, that the nutrients it contains act as fertilizer. It is different than scheduled or weather-based irrigation. Paul James is product manager for Midland, Texas-based Just Water Savers, USA, Inc. He’s originally from Australia, where he first developed—and still sells— the graywater system he designed.
James says his “biggest argument with landscape professionals is getting them out of their habitual mindsets.” He cites this example. “In Tucson, they have a lot of mesquite trees. The trees have adapted to the desert environment by putting taproots down to pull the moisture out of the deep sub-slope. Landscape people have tried to encourage that. They believe they must irrigate twice a week at the most, and do it heavily, to get down to the taproot. They’ve been doing that for years. But taproots don’t hold trees up. Trees under five years old will still blow over in a storm.”
Graywater flows immediately, as soon as taps flow or water drains. “If you water daily, there is a capillary effect,” says James. “Plants and trees will keep their roots up, where the water is, which is also the nutrient-rich soil. You’ve effectively formed a water blanket in the soil, three to four inches thick. If the conditions are right, the roots will go five times past the diameter of the canopy. So you get this huge web of roots, which is a much stronger stability anchor for a tree than a taproot is.”
The soap issue
Graywater systems will be a hard sell for your clients if they have to go out of their way to buy special laundry or bath soaps. Fortunately, they don’t. The two main soap ingredients to avoid are salt and boron.
(Bleach is also a no-no.) Most laundry detergents have a certain amount of salt, but a salt buildup is really only a problem with clay soils.
It’s a little different with subsurface drip. “If you use regular dripline, even if you filter the water at the appropriate level, when any detergent dries out, it creates a film,” said James. “The typical .6 or .7 gallon-per-hour flow rate is not enough to dissolve that. Next time the water comes through, another microscopic layer of detergent is left behind. In six months, you’ve got clogged emitters.”
There are two ways around this, according to James. Either use highflow emitters that put out two gallons per hour, or flush the system every three months with either gray or potable water at higher pressure, at least 50psi.
“The challenge with graywater is that every home is different, and so is every plumbing scenario and every landscape,” says Allen. She describes a graywater installation as “kind of a hybrid of a plumbing system with a landscape irrigation system.”
Most of Mytko’s clients are typical suburban homeowners. Does he find graywater a hard sell to these people? “Nineteen out of 20 times, I have to suggest it. They want to know, ‘How much does it cost, and is it worth it?’” His answer is that the return on investment is “much better than rainwater harvesting, and the payback is a lot faster.” Most of them have come back to him saying that their water bills are a lot lower. He says that the type of client who is most interested in doing graywater is already eco-conscious, with “solar panels on the roof, and a Prius in the driveway.”
You would think that installing any system in a new-build situation would be easier. Not according to Mytko. “If someone is building a new house and they want to plumb it for graywater, then there’s a whole lot of regulatory hoops to jump through. They could make that a lot simpler.”
Graywater is coming your way Graywater is a growing trend, along with all other water-saving initiatives, like smart control and drip irrigation. We’re going to be seeing more of it. In Tucson, there is already a water-harvesting mandate for any new commercial development or redevelopment in the city, as well as water-harvesting rebates from water utilities for residents. (Water harvesting includes graywater). It’s a safe bet that other cities will pass similar measures.
Climate change and severe, persistent drought will continue to drive the demand for graywater. The time to get educated about it is now, not later. Don’t see it as a threat. See it for what it is: a clear opportunity.