Although the iconic rivers and evergreens of the Inland Northwest give off the impression of infinite local water supply, our regional ecosystems actually tend to be on the dry side.
Much of the south half of Eastern Washington, and reaching a bit into North Idaho, is part of the Columbia Plateau region. This region is an arid grassland full of sagebrush. In the northern half of Eastern Washington and North Idaho is the Northern Rockies ecoregion, characterized by its temperate coniferous forests. This area gets more precipitation, but it still experiences hot summers with low humidity and dry vegetation.
These conditions make water conservation valuable for our local ecosystems and the residents who inhabit them. One great tool for reducing tap water demand and maximizing the benefits of precipitation is a rain barrel.
Harvesting rainwater gets you more out of every spring and summer rainstorm, creating a reservoir of free water for those driest dog days of summer. Another amazing benefit is that collecting rainwater reduces the amount of runoff through the city.
This may seem counterintuitive, and is likely why rain barrels have had somewhat of a bad reputation in the past. Wouldn’t collecting rainwater rob the ecosystem of water that would otherwise return to the Spokane River and the Spokane Valley–Rathdrum Prairie Aquifer? That is true, but it is important to think of the quality of the water after it runs over city surfaces and back into waterways.
Runoff from cities is a significant source of water pollution. It runs across asphalt surfaces, backyards and parks and picks up fertilizers, litter, petroleum residue and more along the way. Runoff can also erode precious topsoil. This means capturing rainfall before it can pick up a lot of pollutants is a win for both the environment and your utility bill.
One thing to keep in mind however is that although the rainwater that is funneled into a rain barrel doesn’t come in contact with the street, it does come in contact with your roof. There is a potential that it could pick up bacteria and other pollutants from bird feces and other animal materials, as well as any herbicides that were applied to the roof to kill algae and moss.
That said, water from roof runoff is perfectly safe to use for watering outdoor landscapes as well as outdoor cleaning projects like washing a car. It is generally seen as safe for growing edible plants, but there are some tips to be cautious. When watering edible plants with harvested water, try to water the soil instead of the produce. The soil naturally filters the water and helps clean it. You can also avoid using it on root vegetables to be extra cautious.
A few years ago the Washington Department of Ecology studied roof runoff and found the most contaminants in runoff from wood shake roofing, which is more common on Western Washington. It is also advised to not water edibles with water from roofs with zinc strips, roofs made of copper, or gutters made with copper.
Other proactive measures are to maintain rain-barrel hygiene and clean and disinfect it occasionally, as well as considering dumping runoff after a long dry spell as it has a higher chance of washing away accumulated pollution.
Rain barrel installation is also surprisingly easy and affordable. Home improvement retailers sell barrels for just over $100. You can visit my.spokanecity.org/publicworks/water/water-wise-spokane for a thorough rain barrel resource guide which takes you step by step through the installation as well as tips for how to calculate your how much water your roof could potentially collect. For 1 inch of rain, a 1,000 square foot roof could collect 600 gallons.