Rainwater Harvesting' refers to the collection and storage of rain. Collection is usually from rooftops, and storage in catchment tanks. Stored water can be used for non-potable purposes such as irrigating lawns, washing cars, or flushing toilets. Rainwater harvesting systems can range from a simple barrel at the bottom of a downspout to multiple tanks with pumps and controls. Before the creation of public water utilities, rainwater harvesting provided water for many American homes. It is still popular in places with limited water resources such as island communities like Hawaii. While we think of ourselves as living in a rainy climate, recent drought conditions throughout Oregon remind us how quickly we can run short of water.

Using purified potable water for purposes like flushing toilets or irrigating landscape is a waste of a valuable resource. Portland residents are asking more questions about the role of conservation in extending the supply of drinking water. Stored water can substitute for piped drinking water for many uses where a high level of purity is not required.

Rainwater harvesting is also effective in reducing stormwater runoff pollution. When rain falls, it is clean, but it immediately picks up pollutants from rooftops and pavement. This pollution is carried into storm drains and then into streams. Collecting stormwater from rooftops and directing it to storage tanks so it can later be used for irrigation or flushing decreases the volume and rate of runoff. The City of Portland encourages on-site stormwater innovations and stormwater management fees are reduced if stormwater runoff is safely retained on-site.  In certain locations, Portland will pay an incentive for the disconnection of eligible downspouts from eastside combined sewers. Please call 503-823-5858 to find out if you have any eligible downspouts.  Click here to learn more about the downspout disconnect program.

For residential projects:
You don't need any permits to use collected rainwater outside the house.

To use it indoors for purposes like toilet flushing, you'll need to apply for a permit. The permit guidelines show how to plumb separate lines for rainwater and city water, and prevent contamination between them. The permit guide can be downloaded here.

To go a step further and use rainwater to replace potable water, you'll need to apply for a permit appeal. The appeal process is used so that the Bureau of Development Services can look over your specific design and installation. It's not an adversarial appeal, more like a way to be sure an applicant has really thought through the installation. Also, that you understand the commitment--once water pipes have been used for rainwater they can't be converted back to city water.

For commercial/multifamily applications:
To use harvested rainwater to flush toilets, you are required to be treat the water with filters, UV and/or chlorinating (usually a combination of the first two and possibly all three).