Napa County Master Gardeners: Harvesting Rainwater | master gardener


It all started with the water bill. That’s how Linda St. Claire, a former UC Master Gardener from Napa County, described her conversion to storing rainwater for use in her garden.

St. Claire’s house is in North Napa, and it has a fairly large yard by city standards, one-fifth of an acre. After being shocked by the price she was paying for water to irrigate her garden, she decided to determine how much water she could collect by capturing runoff from her roof.

St. Claire calculated that she could collect 600 to 700 gallons of water from every inch of rain that fell on her 1,000 square foot roof. Even during a stingy rainy season, it can add up.

St. Claire purchased seven used 55-gallon barrels for $20 each. A barrel can fit in his Prius. She also has a 200 gallon barrel that she got with the help of a friend with a truck. The barrels only require scrubbing once a year with food grade soap and a good rinse. Rainwater collected this way is not drinkable, but it is safe for watering a yard.

People also read…

St. Claire took a master gardener course in how to harvest rainwater and set up drip irrigation. She also took advantage of the City of Napa’s Cash For Grass program to rip out her front and back yards. Its drip irrigation is equipped with sensors so that the plants are not watered when it rains.

St. Claire’s barrels are connected by a “daisy chain” of piping and covered. If you have gutters, you should attach a diverter to filter leaves and other detritus after the first rain of the season. Mesh gutter guards also work. Because of all of its innovations, St. Claire’s yard was featured on a Bay Area Water Wise Gardens tour.

According to the Bay Area Stormwater Management Agencies Association, St. Claire’s rainwater-saving method is suitable for homes with roofs that drain to downspouts. You need a firm, level surface for the drums because a filled 55 gallon drum weighs over 400 pounds. Some people tie the barrels to their house, though St. Claire says her barrels could have ripped the wood siding off her house if they had been tied in the 2014 earthquake.

The area where you intend to use the water should be nearby. You should have an overflow path to your storm drains in case the rain barrel overflows.

My grandmother had rain barrels all over her farm in West Virginia. We didn’t fall in and they didn’t fall on us, but these days people are more cautious. Make sure your barrels have lids and that children understand that they are not toys.

Although you can’t find barrels for $20 like Linda did, it’s worth looking around. Barrels will pay for themselves sooner than you think. I’ve seen all types of containers for storing water, from huge “water bladders” for serious farming to thin, flat containers that stand next to a fence and out of sight, especially with plants in front.

Even if you collect rainwater, you must follow the guidelines for saving water. Water in the morning or evening, when it is cooler. Water the soil, not the plants. Use compost and mulch around plants and trees to retain moisture. Get rid of weeds; they compete with your plants for water. Check for water leaks.

Water only when your plants need it. If a handful of soil clings, you can wait. Prioritize your plants; mature trees and shrubs should be given higher priority than easily replaced annuals and edibles. It takes some cruelty, of course.

Looking at St. Claire’s garden, I felt a missed opportunity. I had thought about installing a rain barrel, but the past two years have lulled me into thinking it will never rain again. Then we had the December flood. It’s only January, so there’s still a chance for more.

When I visited St. Claire’s property, she was preparing it for spring planting. Its landscape contains many California natives, but the lion’s share is devoted to food crops. It has peach, pineapple, guava, pomegranate, honeycrisp apple, Asian pear, lemon and fig trees, as well as bushes of elderflower, raspberries, blackberries and olallieberry, as well as vegetable beds. St. Claire’s garden produces a cornucopia, and its abundance would not be possible without its harvest of rain.

Library talk

The Napa County Master Gardeners will be giving a talk on “Creative Cucurbits: Loofahs and More” on Thursday, February 3, from 7-8 p.m. Save room in the garden for a few crazy cucurbits and learn how to prepare them for your own use or as gifts. Sign up to receive the Zoom link at

Food Culture Forum

The Napa County Master Gardeners will host this forum on “Planning, Record Keeping, and Crop Rotation” on Sunday, February 13 from 3-4 p.m. Sign up to receive the Zoom link at

Do you have questions about the garden? Contact the Master Gardener’s Help Desk. The team is working remotely, so please submit your questions via the diagnostic form, sending photos to [email protected] or leaving a detailed message at 707-253-4143. A Master Gardener will answer you by phone or e-mail. For more information, visit


Comments are closed.