Water, water everywhere
Harvesting winter’s rain to keep summer’s soil moist
In the heat of mid-July, Brian Ladwig-Cooper of Gaia Creations Ecological Landscaping scooped away some packed-down mulch that filled an earth basin that he had dug in his yard. He then stuck his hand into the ground.
“It was still moist, and the water hadn’t been on at all,” Ladwig-Cooper recalled. The basin—a large hole dug out of the ground and stuffed tightly with twigs, sticks and leaves—was the dead end of a trench (also stuffed with mulch) that connected the basin to the downspout of the house’s gutters. Fruit trees, five feet away from the basin and more than 50 feet away from the house, received enough gutter water from the winter rains to stay irrigated into the middle of summer.
The trench and basin are flush with the landscape. This is Gaia Creations’ permaculture version of rainwater harvesting: no barrels, no pipes, no expensive equipment—just slight alterations of the landscape that anyone can do with a shovel.
“So many people’s gutters just dump right onto the ground or down the driveway into the storm-water system, and it’s totally ineffective and unused,” explained Stephanie Ladwig-Cooper, Brian’s partner in both life and business. She was interviewed at their home in south Chico’s Barber neighborhood. “Without catching it in a container, this is what we’ve found can be done, and it’s the best we’ve found so far.”
The captured water percolates from the basin into nearby soil, keeping it moist late into the summer. As a result, nearby ornamentals, landscape trees, fruit trees and other perennials can skip regular waterings for most of the year, which significantly reduces water usage.
Permaculture—an approach to design that seeks to replicate the interwoven and overlapping elements of natural ecosystems—is the driving force behind the system. It aims for rainwater-catchment systems that “mimic natural rainfall patterns, [by] allowing rainfall to infiltrate, not erode, to recharge our groundwater, and … to supplement food crops with adequate moisture,” Stephanie explained. This multiple functionality of the system is key in the world of permaculture design, where each component builds upon and complements the many other parts of the landscape.
Stephanie scribbled down a long formula to determine how much water pours down the gutters of a house in an average year: Collection area’s square footage, times annual rainfall in feet, times conversion factor, times runoff coefficient for asphalt-shingle roof. The angle of the roof, she said, does not significantly alter the number. Chico’s 26 inches of average annual rainfall equals 2.1 feet. The conversion factor is 7.48 gallons per cubic foot. And, for those of us with an asphalt-shingled roof, which absorbs a small amount of the rainwater, the coefficient is 0.95. (For those of us with other roofing materials, just leave that one out.)
Stephanie plugged in numbers for a 1,000-square-foot house: 1,000 x 2.1 x 7.48 x 0.95 = 14,922.6 gallons. Almost 15,000 gallons of water a year, on a small house. With the passive harvesting system they have in place, Brian said, “all this water is going to be sinking into the root zones of all the trees. So it just stores this massive underground bottle of water.”
“It’s one really important element for drought-proofing your property. … The less we focus on municipal water sources, the better,” offered Stephanie.
Mike Pembroke, Chico dis-trict manager at California Water Service Co., agrees. Here in Chico, “our biggest [water] demand is residential irrigation,” he said, adding that he loves the idea of harvesting rainwater.
Chico drinking and irrigation water is “100 percent groundwater,” pumped out of the Tuscan Aquifer, which runs below Chico, Pembroke explained. “It would be nice if we could capture more [rainwater] and put it to use.”
Cal Water’s supportive stance runs contrary to a small handful of water municipalities in other parts of the country, however. In 2008, a Utah Toyota dealer’s rainwater-catchment system was briefly shut down by authorities because the dealer did not have water rights to collect rain. In contrast, many states in India have made rainwater-catchment systems a mandatory feature of newly constructed buildings, according to www.rainwaterharvesting.org.
“If you use that [captured] water to lessen some of those demands on the aquifer, and use that water to irrigate around your house, that would be wonderful,” said Pembroke. But he warned that “if you’re capturing it in a barrel, you have to be really careful with it” to ensure pathogens, mosquitoes and unhealthful microbes don’t flourish.
Barrels, common devices for rainwater catchment, “can be a pain for management, to keep all that clean,” said Stephanie. They are also vastly more expensive than digging a trench and filling it with the garden’s trimmings, as the Ladwig-Coopers do. And, at just 55 gallons per barrel drum, you’d need to purchase hundreds of them to capture the amount of water that the basins do in the ground.
The system isn’t foolproof, however, nor does it work for all back yards. Houses built on lava cap, like those in California Park, simply won’t have enough soil to store the water, explained Brian.
Those with soil high in clay may find that the water percolates very slowly, which can turn a backyard trench into a waterway. Before giving the idea up, though, Stephanie recommends checking soil survey maps (websoilsurvey).Title the visitor sees.
Proper location of the basins and trenches is very important, Stephanie pointed out. “You need to make sure you’re keeping the trees at least three feet away from them.” If they’re too close, she said, “they’re not going to do as well because [they may get] waterlogged a little bit.” In addition to knowing the soil’s capacity, paying attention to the natural contours of the yard is also crucial. “Anyone who’s downslope from you could be really affected by your water harvesting,” Stephanie warned.
The Ladwig-Coopers are impressed by how much water their rainwater-harvesting system handles, and confident it can be replicated easily and cheaply in most Chico back yards.
“It’s amazing how many gallons! It really adds up,” said Brian.