Nuts + Bolts: Showers to Flowers

Enlarge Image Image Gallery The indoor graywater-irrigated planter bed in Wellfleet Audobon Sanctuary, Wellfleet, Massachusetts, manages all of the graywater from the building’s sinks. Treated water also flows to the exterior gardens to irrigate and fertilize the plants. Gerard Ives Architects

Reusing household graywater to irrigate plants, flush toilets, and wash clothes is a smart way to avoid rising water costs and preserve valuable resources.

When you wash your hands and then watch the water slip down the drain, do you ever wonder if there’s a less wasteful way to make use of it? Take heart! Increasing numbers of home­owners are using the water that drains from showers, tubs, and washing machines—known as “graywater”— to irrigate plants, flush toilets, and even wash clothes.

A wide variety of systems and components are available to filter, treat, and use household graywater—from ponds and aerobic planter beds to peat filters, sand filters, aerobic aquatic systems, and reverse osmosis membranes. “It’s all a matter of context,” explains Art Ludwig, author of Branched Drain Graywater Systems (Oasis Design, 2000). Because of climate, environmental conditions, costs, and laws, what works for Southern California might not work for the Northeast, Ludwig says.

Although it’s difficult to generalize, here are the basic components and guidelines for creating your own graywater system.

Filter It

Graywater must be filtered to remove particles and dirt that can clog pipes and soils. This is especially important for washing machines, because many modern clothes contain fibers that do not biodegrade. Filters designed to be installed at each source of graywater include thirty-micron filters, which are connected to sink and laundry drains, and grease interceptors (typically made for kitchen sinks), in which grease floats to the top and heavy solids fall to the bottom. Some systems catch and filter graywater flows with peat, sand, and other media. Higher-tech filter options include reverse osmosis systems, which push effluent through porous membranes.