But the idea became a reality in 2009 when we moved from a hillside property to our restored 1928 bungalow in downtown Napa. With help from websites and the water- resource specialists from the City and County of Napa, we designed and created an urban backyard rainwater harvesting system.
A rainwater harvesting system captures and stores rainwater for later use. It reduces demand on the existing water supply. The stored rainwater can be used for landscape irrigation, livestock watering and fire protection. It is an alternative water source that helps in drought times.
Systems vary in size and complexity. We chose a simple system that would collect as much water as our space would allow.
The first component of a water harvesting system is a catchment surface, such as a roof. The size of the catchment determines the amount of harvestable water.
The second component is the conveyance—the pipes, gutters and downspouts that guide rainwater to the storage location. Third is the inlet, where the water enters the storage container. It should have a fine-mesh screen to prevent mosquito breeding and keep out debris.
The fourth element is the storage containers. Tanks, barrels and cisterns come in a range of sizes, from a few hundred gallons to thousands of gallons. Common tank materials include corrugated steel, concrete, wood, fiberglass, polyethylene and polypropylene. Each material has different costs and benefits.
Another component of the water harvesting system is siting. Ideally, the storage tank should be close to the point of use and above ground to take advantage of gravity. Yet another component is the outlet, where the water leaves the tank. The final consideration is usage, or how you intend to use the water you store.
Bearing all this in mind, we determined that the east side of our property was the most logical place to site our tanks. It was flat, in a narrow part of our yard and not visible from our back or front yard. It was also close to our non-edible landscape plants and offered easy access to the gutters draining water from our roof.
Our roof is flatter than most so water drains a bit more slowly. (If you want to calculate how many gallons of rainwater you can harvest, the website rainwaterharvesting.tamu.edu can help you. We can harvest about 560 gallons from three inches of rain.)
For phase one of the project, we purchased a 305-gallon opaque plastic tank and six used wooden wine barrels that could store a total of 330 gallons. An 18-inch-high, pressure-treated wood base was built for the plastic tank, and used metal wine-barrel racks supported the barrels. All these storage containers sat on a three-inch base of crushed blue rock.
Thanks to our house remodeling, we had new gutters and downspouts to drain the east-facing roof into the tank and barrels. Some systems connect multiple tanks so that when the first tank is full, the others fill in succession—a “daisy chain.” But we decided to do this by hand with a connecting garden hose and gravity.
When the first rain came, it was amazing how quickly that 305-gallon tank filled up. In raincoat and rubber boots, my husband began moving hoses and filling wine barrels.
That first spring, we used all the stored water by June. We knew that Napa’s supply of rainwater exceeded our storage capacity, so we increased our capacity. Why not? It was exciting to collect rainwater to irrigate our plants.
The following winter, we increased our storage with an 85-gallon plastic tank from Home Depot. To our dismay, the wine barrels had shrunk while empty, and now they leaked. We learned that wooden barrels must remain at least half full to prevent leakage. Also, keeping gutters clean is critical. And at some point, the sediment in the storage tanks needs to be removed.
We needed more storage. We had read that homeowners in the Napa River watershed could receive a rebate—up to $500 per household—for rain barrels and cisterns installed to capture storm water runoff. We purchased a 500-gallon tank and applied for the rebate. When full, this tank was going to be heavy. On top of the crushed blue rock, this tank now sits on two layers of pressure-treated wood with cinder block in between.
It’s August and the water from last winter is almost exhausted. We use it carefully. It’s perfect for mixing with composted worm castings to fertilize ornamental plants and shrubs. Now, in phase three, we are anxiously awaiting winter. Let it rain, let it rain, let it rain.
Learn more about setting up a rainwater harvesting system for your household at www.napawatersheds.org/rainwater or call Deborah Elliott, Napa County Water Resource Specialist, at 707-259-5969. Alternatively, view my garden on the Napa County Master Gardener Garden Tour (details below) and speak with Deborah or with Frances Knapczyk from the Napa County Resource Conservation District.
Workshop: Napa County Master Gardeners present a workshop on “Edible Landscape Design” on Saturday, October 5, from 10 a.m. to noon. Location is American Canyon Library,300 Crawford Way in American Canyon. Design your garden to be both beautiful and edible. Learn what to consider and how to integrate edible plants into your ornamental garden. Bring a detailed plan of your garden to work on with guidance from U.C. Master Gardeners. Learn about books to help you with your design from Napa County Library as part of the Eat, Move, Read program. Seating is limited. Register online at http://ucanr.edu/ucmgnapa or call 707-253-4147.
Garden Tour: Napa County Master Gardeners will host a self-guided garden tour, “Down the Garden Path,” on Sunday, September 22, from 10 a.m. to 4 p.m. Visit seven unique gardens in and around downtown Napa, all maintained by Master Gardeners. Tickets: $25 advance/$30 day of event. For more information and to purchase tickets, visit http://ucanr.edu/ucmgnapa or call 707-253-4147. Find us on Facebook under UC Master Gardeners of Napa County.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions?