Gray water can solve irrigation issues in some gardens

By February 17, 2011 Sustainable Landscaping 54 Comments

By Jillian Steinberger
Contra Costa Times correspondent

When it comes to gray water systems, there are lots of questions. The most important ones to answer are what system do you need, and what can be done with it.

As gray water systems gain acceptance, we’re learning that they can easily and successfully irrigate Bay Area gardens. Both “simple systems” popular among do-it-yourselfers and high-tech installations making inroads into the public, commercial and high-end residential sectors can produce amazing results.

Lush, beautiful landscapes are more than possible with greywater.

Lush, beautiful landscapes are more than possible with greywater. Image: John Russell

But each type presents a unique set of issues.

Keep in mind that with the newly legal low-tech systems, gray water is applied to the landscape as it is produced. There is little control over the timing and duration of irrigation. When you wash clothes or take a shower, the water is diverted to the landscape.

A picture of a valve/switcher above laundry, that is clearly marked for safety. Label shows how to turn handle to direct greywater to landscape or sewer Image: Laura Allen

A picture of a valve/switcher above laundry, that is clearly marked for safety. Label shows how to turn handle to direct gray water to landscape or sewer. Image: Laura Allen

This is fine in simple landscapes with sturdy plants that can take irregular watering, but not for more complex garden designs.

A favorite strategy among permaculturalists and green gardeners is to irrigate fruit trees and fruiting vines such as kiwi with gray water, which yields excellent results.

On the other hand, says landscape contractor John Russell, high-tech systems that use a sand filter to clean gray water operate about the same as a traditional automated drip irrigation system with controllers and valves. The timing and duration of watering is set by the irrigation controller, and gray water is applied through subsurface irrigation.

Russell, who installed the Sunset Idea House’s gray water-integrated garden in San Francisco, says some landscapes may not like any form of gray water.

“Gray water tends to be alkaline so plants that like acidic soils will generally not like being irrigated with gray water,” he says. “But most plants are accustomed to or tolerant of alkaline soils and will be fine with gray water irrigation.”

Gardeners concerned about the alkaline can consistently add organic matter to the soil, which adds acidity and can help neutralize the alkaline nature of gray water. Acid-loving plants such as rhododendrons, azaleas and camellias will not tolerate gray water, but an abundance of California natives and other plants thrive in alkaline conditions.

What branch drain looks like in the ground. Pipes for a branched drain system Image credit: Laura Allen

What branch drain looks like in the ground. Pipes for a branched drain system. Image: Laura Allen

Plumbing Contractor Christina Bertea, who teaches installation classes around the state as a member of Greywater Action, says the question of what system is right for you boils down to money.

“How much,” she asks, “do you want to spend? If you have an unlimited budget, you can do anything with gray water. If not, the simple low-tech systems we teach are best suited for larger plants like trees, shrubs, perennials and vines.”

The systems also are well-suited to bioswale plantings, with plants that easily adapt to wet or dry conditions.

Although relatively few landscape professionals have the skill set to install gray water-irrigated gardens, the niche is rife with innovation. Some of California’s most forward-looking environmental engineers, landscape architects and ecological designers are creating plans specifically for gray-water integrated gardens.

One lush design strategy called “constructed wetlands” uses water-loving plants such as taros, reeds, rushes and cannas that can digest the high nutrient load of gray water, thereby providing a cleansing function. Some plants even can process heavy metals.

Nik Bertulis, an ecological designer with the Dig Cooperative who teaches a class called From Dams to Greywater at Oakland’s Merritt College, says constructed wetlands can have “a tremendous capacity to bioremediate neo-chemicals and pathogens.”

For this reason, constructed wetlands are a great landscaping option for a yard with toxic soils — contaminated with heavy metals or pesticides.

Beyond sustainability, constructed wetlands are an aesthetic option for people who want to play with water-loving plants. Different types of wetlands work well in California gardens; they are all lush, and range from mini-estuaries and wet meadows to the tropics. Although conventional wisdom recommends drought-tolerant plantings in California’s summer-dry, winter-wet climate, gray water allows designers to use a plant palette that otherwise is difficult to justify here.

Constructed wetlands done right are safe and provide rich wildlife habitat, ecological landscape designers say. They range in size from container plantings in recycled bathtubs to estuaries and ponds of virtually any size. They fit into small and large yards, and budgets of any size. In Europe, designers are actually constructing wetlands of scale that look identical to lakes, sometimes integrated with “natural” swimming pools. These make a grand impression, although swimming areas should never use untreated gray water.

Such projects are not yet permitted in the United States, but experts say we’re slowly moving in that direction. The Bay Area seems to be at the center of the gray water movement.

You can see examples of how gray water systems work in public sector projects. Russell designed the systems in use at the Academy of Sciences, Crissy Field Center and Alcatraz Island. Geoff Hall of Sentient Landscape in Sebastopol recently designed and installed landscapes for two Gold LEED-rated hotels: the 9-acre Atman in the Anderson Valley and the 4-acre Gaia Hotel in Napa Valley.

Brent Bucknum, founder of the Oakland ecological engineering firm Hyphae Design Laboratory and the community-based nonprofit the Urban Biofilter, also has created a number of advanced gray water systems, including a 70,000-gallon-a-day system at a new UC San Diego dormitory that provides irrigation to the landscape and living roofs and an off-the-grid home in Sonoma that uses constructed wetlands to treat both gray and black water.

“We are developing extremely low cost solutions to gray water and black water reuse in Haiti and Tijuana,” Bucknum says, “and we are developing high tech smart phone controlled systems.

While some gray water and permaculture designers question the high-tech systems, Bucknum sees hope in the blending of ecology and technology.

“I think there’s a sweet spot,” he says, “where they come together.”

Planting Tips

Fruit trees and edibles: Gray water is a popular way to irrigate fruit trees. It is also fine on edible plants in which the gray water does not touch the parts you eat. So, never use gray water on root crops such as carrots, potatoes and beets, or on leafy greens such as lettuce, spinach or kale.

Lawns: Unfortunately for lawn-lovers, gray water is not a sustainable solution for lawns. “Lawns are the hardest type of plant to water with gray water,” says Greywater Action founder Laura Allen. “I don’t recommend it.”

Native plants: Many California natives can take alkaline soils. In fact, our official state soil is Serpentine, which in extreme cases can be up to 100 percent mineral, free of organic matter. So natives can be highly compatible with gray water.

Constructed wetlands: Whether in a container or your whole backyard, constructed wetlands are the ultimate new landscaping challenge, offering tremendous sustainability benefits plus a whole new realm of water-loving plants to play with. Check online for appropriate plant lists and information from state and federal government agencies, universities, environmental engineers and landscapers. Hydrozone: When incorporating gray water, it helps to keep plants with similar water needs together within a zone. “If people place their water loving plants in an area accessible with gray water, and then plant their drought tolerant plants in other areas of the yard, they can eliminate the need for potable water irrigation completely,” Allen says.

Reading material

The New Create an Oasis with Greywater: Choosing, Building and Using Greywater Systems by Art Ludwig (Oasis Design, $20.95)

Builder’s Greywater Guide: Installation of Greywater Systems in New Construction & Remodeling by Art Ludwig (Oasis Design, $14.95)

Rainwater Harvesting for Drylands and Beyond by Brad Lancaster (Rainsource Press, $24.95); http://www.harvestingrainwater.com/greywater-harvesting


Gaia’s Garden: A Guide to Home-Scale Permaculture by Toby Hemenway (Chelsea Green Publishing, $29.95); http://patternliteracy.com

Vendors and Products

Clean Water Components, cleanwatercomponents.com — Gray water kits and plans for simple systems, and a large selection of parts and fittings

Aqua2Use, http://aqua2use.com — State-of-the-art packaged systems that collect, treat, and store water, with options for indoor and outdoor reuse.

ReWater Systems, http://rewater.com — High-end automated packaged systems that filter, store and irrigate. All packages come with a unique 21-station gray water-compatible controller.

Nubian Water Systems, http://www.nubian.com.au/ — Manufactures technically advanced water treatment and recycling products for the domestic, commercial, industrial and mining markets

Education

The Water Institute at Occidental Arts and Ecology Center, Occidental, www.oaec.org


Regenerative Design Institute, Bolinas, http://www.regenerativedesign.org


Sonoma State University’s Sustainable Landscaping Certification Program, Rohnert Park, http://www.sonoma.edu/exed/sustainable-landscape


Merritt College’s Landscape Horticulture Department, Oakland, http://www.merrittlandhort.com


Ecology Center’s EcoHouse, Berkeley, http://www.ecologycenter.org

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