Rain barrel. Photo by Ecoyards.

We’ve been enjoying unusually warm, dry and sunny weather in Seattle lately. The lack of rain means it’s a great time to tap your rain barrels to water your plants. Most of you know that rain barrels are used to catch rain water and store it for later use. We get a lot of questions about rain barrels from customers, so we’ve tackled a couple of them here.

Can I use my rain barrel water for vegetables? Unless you get your water tested, there’s really no way to know for certain whether the water that runs off your rooftop and into gutters and then your rain barrel is completely safe for edible plants. The water could contain heavy metals (depending on what’s in those roof shingles), or fecal coliform and other bacteria from bird or other wildlife droppings. The safest bet is to use the water for non-edible plants only. If you must use the water on vegetables (depending on your personal comfort level), here are some tips: water close to the ground through a drip system; keep the water in the soil and away from fruits, veggies or foliage; avoid watering lettuce or other plants that are grow close to the ground; and always thoroughly wash your produce with drinkable water before eating. The city of Seattle’s Rain Barrel Guide recommends not using rainwater for plants if your roof is made of copper, or if it has wooden shingles treated with any chemical such as chromated copper arsenate to make them resistant to algae, moss or lichen.

How do I prevent overflows during storms? Install an overflow hose adapter, which allows water to flow through a small hose and drain to a nearby lawn or landscape bed. Make sure you direct it away from a basement or your foundation.

How much water can I actually collect from my roof? A general rule of thumb says that you can catch about 600 gallons of water for every 1 inch of rainfall on a 1,000 square foot roof. If you want to do your own math, the city of Seattle has a good formula in its rain barrel guide to help you out.

By now, most of us probably have a rain barrel or two that we use to catch rainwater from our roof. These red 50-gallon barrels have become common features around Seattle, Burien, Normandy Park and other cities, especially because you can get them at a nice reasonable price and they’re easy to set up. We currently have three of them at our house, and we’re able to use the water that we catch to irrigate our trees, container plants and lots more. But as many of you know, the barrels fill up quickly during a rain event. So what to do if you want to harvest more rainwater?

Photo of cistern from city of Seattle Rain Wise program

Enter the cistern. These larger containers can store hundreds or even thousands of gallons of water at a time, which conserve water and improve drainage issues at your property. Think: no more soggy lawn always getting flooded with inches of water when it rains! Because cisterns hold water during a rain, storm or snow event, less water rushes into our streets, drains and sewer systems. That means fewer sewer overflow problems and fewer pollutants washing unfiltered into our creeks, rivers and Puget Sound.

Cisterns aren’t much different from rain barrels. They’re just much larger. Home cisterns can capture anywhere from 200 to 1,000 gallons of water. They can look attractive, too, and blend in with your landscape. Unlike rain barrels, cisterns require a bit more planning and installation. Because they’re considerably larger than rain barrels — and will be heavier because of all the water they’ll hold — you’ll need a good foundation for it. Ecoyards is a licensed contractor registered with the city of Seattle RainWise program. We’re also licensed by the state, of course, but this program registration allows us to install cisterns, or rain gardens, at certain homes that are eligible for city rebates under the RainWise program. (Read more about the rebate program for rain gardens in our previous post).

Whether or not you’re eligible for a rebate, we’re happy to help you sort out all the details. If you’re interested in installing a cistern but don’t want to tackle it yourself, we can help you calculate how much rainwater can be harvested off your roof and then recommend a good size, shape and foundation for it. We’ll figure it all out for you, from pipes and connectors to the right Northwest native plants for your site. Cisterns can be made of many materials, such as plastic, sheet metal, wood or even concrete. You can install them underground, partially underground or above ground. For those who are in the Ballard neighborhood, and eligible for a city rebate, we also can help you navigate the rules and requirements. Please email us and we’ll help you figure it out.

The past week has brought gorgeous sunny weather — even surprisingly high temperatures — to the Puget Sound area. That’s been great for our vitamin D-deprived bodies, but our plants may be feeling the heat. This week has been the perfect time to tap into your 50-gallon rain barrel (hopefully you have at least one installed at your house) to use up the water that you’ve stored from the spring. (For where to buy in Seattle, go to the Seattle Public Utilities Web site; for King County information, check out this site).

Rain barrels allow you to catch rainwater off your roof during rainy days, and to store it to use during dry periods. Seattle relies on mountain snowmelt for its water supply, so water is precious during summer months (especially if we’ve had less snow than usual the previous winter). Water rates also jump in the summer months, so rain barrels can help you save money and conserve water.

We have two rain barrels that we bought from the city of Seattle and have set up in the backyard to water our non-edible plants. Should you use the rainwater from your roof on plants that you eat? We err on the safe side and use the water exclusively for our non-edible plants. We have plenty of other trees and shrubs to water, and our vegetables are already on an efficient drip-irrigation system.

Over the years, I’ve found that the easiest way to water plants, especially trees, is to buy a few cheap 5-gallon buckets, poke a hole near the bottom of each bucket and set them under the rain barrel to fill one at a time.  Once a bucket is full of water, I’ll set the bucket out near the base of a tree that needs water while another bucket is being filled under the rain barrel. Trees, shrubs and other plants like the slow, deep irrigation that trickels out from the small hole in the bucket. The slow-drip allows the water to seep into the soil more deeply rather than just running off the ground surface or evaporating.