After the Lawn: Greywater
So far in After the Lawn, the imaginary homeowners have done everything right on their 5,000-square-foot lot around their 1,200-square-foot home. They've slow-watered shade trees with hoses while steadily removing lawn. They've improved soil absorbency while waiting to put in "drought tolerant" plants next rainy season. They've put in rain barrels and are working on a long game to break up pavement and reshape earth to capture all the precipitation that rolls off all their hardscape before it hits the driveway apron. Yet, as rainy season ends and the long dry season begins, their landscape will still need supplemental water.
In years to come, this may not be available from the public's potable supply. So the imaginary homeowners are looking to their washing machine and bathtub for a new source. With a little help from a calculator and information sheets from the US Environmental Protection Agency and the Portland Water Bureau, they found that the combined discharges of these were sending 876 gallons a day, or roughly 32,000 gallons a year, of "greywater" down the drain.
Unlike "blackwater" from the kitchen sink, dishwasher, and toilet, greywater from a tub or washing machine may be legally diverted to the landscape. The imaginary family's output even with low-flow showerheads is so large that it exceeds the total amount of rain that fell on a typical 5,000 square foot Los Angeles County lot this year. Put another way, a tub-and-washer greywater system for our test case house would have taken a drier-than-average year (9 inches of rain) and turned it into a respectably wet one (18 inches). Best, greywater can still flow outdoors in the summer.
For existing homes, simple laundry-to-landscape systems may be done without a permit by anyone who is reasonably handy. Or so say the three different greywater activists interviewed for this article. Cost of parts shouldn't exceed a couple of hundred dollars for DIYers, they say, though it may run three times that for those who need it installed.
Before putting in a laundry system, the granddaddy of greywater advocacy, Art Ludwig of Oasis Design, recommends doing a comprehensive water-use audit for your property. If you have a new, hyper-efficient clothes washer, he warns, laundry-to-landscape may be, ahem, a wash. It may not put out enough water to make it through a divider splitting the water between two fruit trees.
The best way to figure out how much water your washer might use is to measure it, says Laura Allen of Greywater Action. Allen's group will be giving a bilingual laundry-to-landscape workshop at Agua-Flow Irrigation Store in Culver City on April 23. Those concerned about the impact of household detergents on plants should read the study that Allen conducted on 83 greywater systems in Northern California. Installed correctly with mulch basins that biodegrade nutrients in the wastewater, there were almost no differences in soils irrigated with potable water. "The soaps that we found to be good included Ecos liquid laundry detergent, Bio Pac, Vaska, and there were more," she says. Allen does not recommend Seventh Generation for greywater systems because of concerns about boron.
Do the kind of water-audit recommended by Ludwig, however, and the mother lode of greywater clearly comes from baths and showers. Retrofitting these requires paperwork and permit fees. Los Angeles City Councilmember Paul Krekorian hopes to incentivize conversions by ultimately waiving the fees. The city's Green Building Division Chief Osama Younan confirms that, while there are still typically plan check and permit fees running $100 each, his department is working on new reforms as part of the mayor's emergency drought directive.
The overall cost of a bathroom retrofit will have many variables, including the number of bathrooms, need for pumps, and complexity of the dispersal system, according to Leigh Jerrard, a LEED-accredited architect and founder of Greywater Corps. Provided that a house is not on a slab, in which case the pipes will be inaccessible, a branched drain system for a typical home might cost $4,000. Jerrard and Krekorian are pushing for a change that would require all new construction to come greywater-ready.
From Tucson, water conservationist Brad Lancaster suggests cutting out the middleman. Shower outdoors! Provided people don't double their water use merely trying to get warm, and the drainage is advantageous, outdoor showers can be the simplest, most cost-effective greywater conversions going. As a salute to Lancaster, and nod to anyone who has ever tried to wash a dog indoors, this week's back yard elevation has a patio shower. Please note that in real-world systems, the flow of the water should not be visible. It would have to be pipe-fed to mulched areas. For sanitary reasons, greywater cannot legally discharge over-ground or be stored. Rather, it must be infiltrated into soil systems that will quickly degrade any impurities.
The imaginary family's washing machine was a bear when it came to plotting discharge in this week's drawings. Fruit trees are a favorite type of recipient plant among greywater installers (no danger of leafy greens tasting like soap or dead skin in your salad.) However, the shade plan done for the case study site in Part Two showed only limited space where a simple run of apple, plum, peach and apricot trees could take advantage of laundry water and get sun.
Happily, however, laundry machines pump water out, so it did look feasible to push the greywater around the garage to fruit trees out in a bright spot by the driveway. (The imaginary homeowners may be told x-nay by an installer.) As for the tub water, grading to the south and east mean that a branch drain system to the front might work on gravity flow, though with such a subtle grade, adding a pump to the job seems prudent.
Given the quantity of water involved, any major greywater plan should be reviewed by a landscape architect. Leigh Jerrard, the premier installer working around Los Angeles, says his waiting list is now three to four weeks long. It's bound to get even longer. This may be a blessing. Converting homes to greywater is expensive. It deserves being done right. But it deserves to be done, if not this year, then next. As no plant can tell you, but anyone can show you, greywater is better than no water.
The next installment of After the Lawn will examine the plant carrying-capacity of the combined rain and greywater systems of the Imaginary Home.
Follow the entire After the Lawn series:
After the Lawn: Part I
Designing Your New Garden
Caring For Your Turf
How to Remove Your Lawn
Planning Your New Garden
How to Design Your New Garden
Managing the Parkway