Pierce County, WA Landscaping Rules: Rainwater Harvesting (2026)

The credit runs through Pierce County's Surface Water Management Utility, which bills every parcel in unincorporated Pierce County an annual service charge under PCC 11.02.050.A. Owners who qualified before October 1, 2016 can keep receiving a credit against that charge under the Pre-2017 Credit Program in PCC 11.02.050.B, which the code reviser's note confirms sunsets on January 1, 2027. Roof rainwater collection systems fall under PCC 11.02.050.B.7: a system sized to hold at least 1,500 gallons per structure for later nonpotable use is credited at the same rate as a 10-year retention facility, while systems built to retain the 25-, 50- or 100-year storm earn the matching higher retention-facility credit tier, as long as the stored water can be used within 24 hours.

Design guidance sits in Volume III of the Pierce County Stormwater Management and Site Development Manual. To qualify, the Owner of Record must submit engineer-stamped 'As Constructed Plans' and an operation and maintenance manual, then file an annual certified maintenance statement by October 1 each year, a recorded hold-harmless agreement, and a recorded inspection-access agreement with the County Auditor under PCC 11.02.050.B.2 through B.5. The maximum credit per parcel is capped at $12,500 for 2021 and each year after through the 2027 credit year under PCC 11.02.050.B.9, with a separate declining-percentage cap for parcels that already exceeded $20,000 in 2017 under PCC 11.02.050.B.10.

Separately, installing the harvesting system itself carries no plumbing permit fee: the fee tables adopted under PCC 17C.10.070, Table 17C.10-1-D, list 'Rainwater Harvesting System' at $0.00 for both 2026 and 2027, though the installation still requires a plumbing permit under the Uniform Plumbing Code adopted at PCC 17C.50.010.