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Two happy rainwater harvesters hugging a cistern. The cistern collects rainwater from their roof.

Two happy rainwater harvesters

Whether you're a Northwest gardener looking to ensure that your plants don't suffer in the long dry summer, or a business owner looking to manage stormwater runoff from your large roof, you may want to consider an old-fashioned technology: rainwater catchment with barrels or cisterns.

Not only will harvesting rainwater safeguard your garden, you’ll also be helping to keep our waterways clean, safe and full of life! When storms occur and large quantities of water go down storm drains, it can pollute local waterways. In some neighborhoods in Seattle, storm drains flow directly into sewer pipes and heavy storms can cause overflows. In the rest of King County, storm drains flow into streams and local water bodies and heavy storms can cause pollution. In both cases, by harvesting the rain that falls on your roof, you are helping keep our waterways clean!

You can buy or make a catchment system. If you have a very large roof or a lot of plants to care for, consider upgrading to a large-volume cistern which can store more water, thus providing for larger gardens and doing even more to safeguard natural ecosystems.

Two happy rainwater harvesters hugging a cistern

Rain tanks come in all shapes and sizes (Photo courtesy of Rain Dog Designs)

Grants and rebates available

If you live in certain parts of King County, you may qualify for a rebate which will cover most or all of your installation costs!

Mother and son on their lawn in front of a sign that says I am RainWise.

Get RainWise and you may be eligible for a rebate!

More information/general resources

Cistern in front of a home porch

Cisterns can fit anywhere!

Rain barrel and cistern (rain tank) sources

Following is a list of some sources to purchase rainwater catchment equipment for pick. You can also try calling your favorite local garden center and ask if they stock rain barrels or cisterns.

*Note: King County maintains this list as a courtesy to the public and does not endorse or guarantee the quality of the service offered or provided.

News and announcements

Check out the RainChangers campaign from Stewardship Partners!

Frequently asked questions

Yes! Washington State has ruled that water rights are not necessary for rooftop rainwater harvesting as long as it is used on site. Click here for more information.

Your initial investment depends on how big of a project you undertake. Some factors to consider:

  • How big is your catchment area (roof)?
  • How big is your garden?
  • How much will you be relying on irrigation rather than rain to water your plants?
  • You may find this Calculator Tool useful in thinking about how big of a tank you need.

And remember, you may be eligible for financial and/or technical resources to help install a rainwater catchment system. Learn more about incentives throughout the Puget Sound region here. 

Most often gravity will provide enough water pressure for your garden hose. If you are having trouble, you can try elevating your barrel/cistern or moving it closer to your garden. If that still isn’t working, there are small inexpensive pumps and drip irrigation systems on the market which will get the job done.
In most residential systems, water harvested from rooftops is NOT safe to drink. There are steps you can take to make your water potable, but they require considerably more intricate and expensive systems. You can read more about various filtration and purification methods here. Before installing a filtration system, be sure to check with the Public Health Department as they have strict standards on water for indoor use.
Credible research says yes (mostly). An interesting overview, including some easy steps you can take to stay on the safe side, was just created by Sightline Institute.
Yes, around the world people use harvested rainwater for flushing their toilets as well as washing clothes, cars, floors, pets, or even themselves! Make sure you know what’s in your water before you use it for anything, as chemicals picked up from your roof or metal gutters can have unintended effects. Using a system that discards the first flush as well as having non-toxic roofing and gutter materials can help ensure water quality. If you plan to use your water for indoor purposes, you’ll need to check with the Public Health Department as special treatment is needed. Arid states with water shortages have more lenient regulations when it comes to allowing indoor use.

Yes, depending on where you live in King County.

Related Topics

RainScapes

Green stormwater infrastructure incentive program.

Stormwater services

Resources and technical guidance to help manage stormwater.

Flood services

Services for residents to manage and reduce river flooding.
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