Rainwater harvesting is the capture and storage of rainwater for beneficial use. Rainwater is considered the cleanest form of harvested water and can be used for toilet flushing, hose bibs, industrial applications, domestic clothes washing, irrigation, water features and other approved usages.
Rainwater harvesting can be an important green building strategy, and can contribute toward credits in both the LEED™ standard and Built Green™ program. For example, rainwater harvesting can help a project achieve stormwater quality, water efficient landscaping, innovative wastewater technologies, water use reduction, and innovation in design credits in the LEED standard. For more information visit the LEED website, www.usgbc.org, and the Built Green website, www.builtgreen.net.
Rainwater harvesting provides many benefits. It can generate savings by reducing utility fees charged for potable water use and sanitary sewer use. It protects our local water bodies such as the Puget Sound, Lake Union and Lake Washington by reducing combined sewer overflows during peak storm events. And, rainwater harvesting conserves water by reducing demand for potable water that is used for non-potable purposes.
Rainwater Harvesting Policy and Procedures
The City of Seattle partnered with Seattle King County Public Health to develop rainwater harvesting policy and procedures titled, Rainwater Harvesting and Connection to Plumbing Fixtures. The policy provides design guidelines and addresses specific regulatory requirements and procedures for commercial and residential rainwater harvesting systems, including system components. The guideline can be obtained online at www.metrokc.gov/health/plumbing/guidelines.htm, or contact Seattle King County Public Health at (206) 296-4600.
Client Assistance Memo
To provide additional technical and regulatory guidance, DPD will have available in early April Client Assistance Memo (CAM) 701, Rainwater Harvesting for Beneficial Use. The CAM provides definitions, explains the benefits of rainwater harvesting, and offers suggestions on system components, requirements and design considerations. CAM 701 also features both a commercial and residential case study that includes the design and system components for the rainwater harvest system. CAM 701 will be available online at www.seattle.gov/dpd/cams, and at DPD’s Applicant Service Center at 700 Fifth Avenue, Suite 2000, Seattle.
As part of Seattle Public Utilities’ (SPU’s) stormwater code update, the draft Director’s Rules address how rainwater harvesting can be paired with detention cisterns. The new code does not allow rainwater harvesting to count toward detention volume, but does offer guidance as to how the two types of systems can be complimentary. Rainwater cisterns are addressed in Volume 3 of the Director’s Rule, which can be found at www.seattle.gov/dpd/Planning/Stormwater_Grading_and_Drainage_Code_Revisions.
Water Right Permit
SPU received from the Washington State Department of Ecology a water right permit to capture and use rainwater that falls on rooftops and structures in the combined and partially combined sewer system. The water right permit clears the way for property owners by removing legal uncertainty. SPU plans to develop initiatives that will encourage and hasten adoption of rainwater harvesting to reduce peak stormwater flows that enter Seattle’s sewer system, and to conserve potable water currently used for non-potable purposes. For a map of combined and partially separated sewer system and additional information regarding the water rights program, visit www.seattle.gov/util/About_SPU/Water_System/Projects/RainwaterPermit or contact Paul Fleming at paul.fleming@seattle.gov or (206) 684-7626.
SPU also encourages homeowners to install rain barrels and use the collected rainwater to water landscapes during dry summer months. For more information on rain barrels and natural lawn and garden care visit: www.seattle.gov/util/Services/Yard/Natural_Lawn_&_Garden_Care/Rain_Water_Harvesting/index.asp.
Incentives
Incentives may be available for rainwater harvesting systems. This year, SPU plans to offer a Stormwater Facility Credit Program, and property owners will be able to apply for the credit to lower their drainage fee. For more information on this program contact SPU at (206) 684-3000. Another source of incentives for businesses and industrial facilities is through the Saving Water Partnership funded by SPU and other local utilities in King County. For more information visit http://savingwater.org/index.htm or contact Phil Paschke, (206) 684-5883 or phil.paschke@seattle.gov.
Seattle Green Factor
The Seattle Green Factor requires new development in neighborhood business districts to meet a landscaping target using a menu of landscaping strategies. The Green Factor is designed to improve the extent and quality of landscapes, while allowing greater flexibility for developers and designers to meet open space requirements. It encourages layering of vegetation in areas visible to the public and along streets adjacent to new development. When used for landscape irrigation, rainwater harvesting can provide bonus credits for the Seattle Green Factor landscaping requirement. A worksheet helps applicants calculate their project’s score, allowing them to try different combinations of features to reach the requirement. For more information visit www.seattle.gov/dpd/permits/greenfactor.