Drainage Rates
The City of Seattle charges property owners a fee for stormwater management services based on each property's estimated impact on the City's drainage system. These fees are billed as a separate line item on King County property tax statements.
Starting January 1, 2025, the City of Seattle changed the drainage rate structure which underlies the calculation of the drainage fee. The current structure improved equity among customers by more accurately reflecting customers' impacts on the drainage system.
Small residential parcels (single-family homes, townhomes, and duplexes less than 10,000 square feet) are charged a flat rate per parcel based on parcel size. All other parcels, including residential parcels over 10,000 square feet and all commercial and industrial parcels, are charged a per square foot fee based on a parcel’s estimated percent hard (impervious) surface area.
Learn more about who pays a drainage bill, how it is calculated, and where to direct payments.
| Parcel size | 2025 | 2026 |
|---|---|---|
| Under 2000 sq. ft. | $235.28 | $247.09 |
| 2000-3499 sq. ft. | $447.08 | $469.52 |
| 3500-4499 sq. ft. | $572.64 | $601.39 |
| 4500-5499 sq. ft. | $672.93 | $706.71 |
| 5500-6499 sq. ft. | $764.98 | $803.38 |
| 6500-9999 sq. ft. | $929.48 | $976.13 |
| Property surface type | 2025 | 2026 |
|---|---|---|
| 0-10% Hard Surface: | $59.82 | $54.23 |
| 11-20% Hard Surface: | $65.11 | $70.91 |
| 21-35% Hard Surface: | $94.46 | $97.01 |
| 36-50% Hard Surface: | $123.19 | $129.37 |
| 51-65% Hard Surface: | $138.77 | $152.60 |
| 66-85% Hard Surface: | $183.25 | $192.45 |
| 86-100% Hard Surface: | $216.17 | $232.15 |
Drainage fees do not appear on your utility bill but are collected with your King County property taxes. The fee is shown on your tax bill as SWM (Surface Water Management) or Drainage. You can view your drainage fee by entering your property tax ID in the King County Property Tax Information System.
Eligible low income customers can receive a credit. Learn more about the Payment Assistance Program.
Related links
Understanding Your Drainage Fee
King County Property Tax Information System