It took a long-awaited rainy day to put this backyard in Lafayette, California, to the test. As it poured, the designer, landscape architect David Thorne (thornela.com), looked out over the contoured landscape, watching water from the roof work its way through the home’s downspouts, under stone bridges, into channels, and finally into planted basins (bioswales). “As each basin filled up with rainfall, it turned into a pond,” Thorne says. “Then the water slowly percolated into the soil. It was magical.” But the real beauty of a rain garden such as this one is how it prevents runoff and replenishes groundwater, critical during drought times. After months with little rain, toxins (as from smog) can accumulate on roofs and paved surfaces; when heavy rains do hit, they carry those pollutants into storm drains and ultimately to the ocean. In a rain garden, however, channels slow down the water, while bioswales absorb and clean it. Yes, the landscaping is an investment—and there are smaller steps you can take to collect water—but it pays off. “A lot of planning and careful engineering goes into a garden like this,” Thorne says. “Yet it looks natural, effortless.”
Slabs of Arizona flagstone form bridges over rock-lined channels. The rocks help slow the flow of water underneath.
Rocks such as this one, partially wedged beneath a bridge, help hold back water in places along channels, so some of it soaks the soil en route.
The simplest form of a rain garden is a shallow basin located at least 10 feet from your house, where you can direct runoff from your roof or paved surfaces. Dig a 6- to 12-inch-deep basin with sloped sides and a flat bottom in fast-draining, well-amended soil. Plant it with species that can take both wet and dry conditions. This 14- by 24-foot-wide basin holds up to 18 inches of water. Grasses and native irises fill it. California fuchsia, which likes dry conditions, grows on the brim. Find more guidelines at ucanr.edu/sites/raingardens.
Attached to a roof gutter, it channels rainwater from the roof into a catchment basin.
Each holds about 50 to 60 gallons of water. The best kinds are made from recycled food-grade plastic with an intake line, spigot, overflow attachment, and removable cover. Place the barrel under a downspout.
A staple in the Southwest where monsoon rains can come suddenly, dry creek beds can channel water to basins in a garden’s low points. Just dig a trench from 2 to 5 feet deep, then line it with stones and sand-colored pebbles.