RainWise Rebate Program
Install an approved rain garden or cistern that manages enough roof runoff.
- Run by
- Seattle Public Utilities and King County Wastewater Treatment Division
- Service area
- Eligible properties in Seattle's combined sewer area.
Program at a glance
- Benefit
- Rain gardens use $13.12 per approved square foot of roof managed; confirm the current cistern rate.
- Who
- Property owners at an eligible address with a feasible roof connection.
- Where
- Eligible parts of Seattle shown by the official map.
- Qualifying project
- Install an approved rain garden or cistern that manages enough roof runoff.
Quick check
Do the main rules appear to fit?
Your answers stay in this page session. The program makes the final decision.
Answer each question for a cautious result.
The rules remain visible here even if the interactive check is unavailable.
The finished result
What project qualifies?
Build an approved system that captures and manages runoff from a qualifying roof area.
Roof runoff is routed into a RainWise-designed rain garden, cistern, or approved combination that passes inspection.
Rain garden
Excavate and install an approved planted bioretention area that receives roof runoff.
Minimum: Current details use a 400-square-foot total managed-roof minimum.
See the full project guide →Cistern
Install an approved 200- to 5,000-gallon cistern connected to qualifying roof area.
Minimum: At least 300 square feet of roof area for the cistern route.
See the full project guide →What the project may require
A product can be one part of the work. The approved project, timing, design, and proof control.
RainWise design and contractor
requiredConfirms feasibility, designs the system, and leads the rebate process.
Use a trained RainWise contractor.
Site work and excavation
conditionalCreates the approved rain-garden or cistern installation area.
Follow the accepted design and pre-inspection result.
Rain-garden soil
requiredStores and filters runoff while supporting plants.
Use a 12-inch bioretention-soil layer meeting the published specification.
Wood-based mulch
requiredProtects the rain-garden surface.
Use a three-inch layer; arborist chips are preferred.
Rain-garden plants
requiredCreates the planted stormwater system.
The design should reach 80% canopy after three years.
Washed rock in selected details
conditionalProtects specific inlets, outlets, armored areas, or trenches.
Use only the one- to three-inch washed gravel or cobble shown in the accepted detail.
Pre- and post-inspections
requiredConfirms the design and completed system.
Pass the RainWise inspection process.
Published formula
Estimate the program maximum
This is a planning estimate, not an approval or promise of payment. The program checks the final eligible amount.
Estimated maximum
$0
The published minimum is 400 approved square foot of roof area managed.
- $13.12 per approved square foot of roof area managed
- The estimate cannot exceed eligible actual cost.
Official path: contractor
How to apply or check the program
- 1
Check the address
Use the official eligibility map.
- 2
Find a trained contractor
Use the program directory and have the contractor test feasibility.
- 3
Complete design and pre-inspection
Confirm the current rate and accepted design before construction.
- 4
Install, inspect, and submit
Use the accepted details and complete the rebate package.
After the program confirms the plan
Planning the approved project?
The trained contractor controls the approved design. Hello Gravel can help confirm and estimate specified soil, mulch, or washed rock only after the contractor defines it.
Possible inputs: bioretention soil, wood mulch, washed detail rock
Review materials from the contractor's planDetails to confirm
- Map eligibility does not prove site feasibility.
- Official sources conflict on the current cistern rate.
Examples that do not qualify
- Rock mulch across the rain-garden bed.
- A self-designed system outside the trained-contractor process.
Questions people ask
Can I build it myself?
RainWise uses trained contractors as part of the rebate process.
Does gravel qualify?
Only as washed rock or cobble in specific approved details; not as garden mulch.
Does the map guarantee a rebate?
No. Feasibility, design, inspections, and funding still apply.
Last verified 8/11/26
Official sources
Use these official sources for current rules, availability, and application details.
- RainWise rebate process — RainWise
- RainWise eligibility — RainWise
- Current RainWise design details — RainWise
- April 28, 2026 RainWise rate bulletin — City of Seattle
More programs to check
Atlanta Post-Development Stormwater Management Ordinance
Cash benefit: none. Required retention: first 1.0 inch of runoff on site.
Austin Water WaterWise Rainscape Rebate
Base: $0.50 per square foot. Turf removal bonus: additional $0.50 per square foot when applicable.
Burlington Blue BTV Residential Stormwater Program
2026 site maximum: $2,000.00. Linked chart permeable pavers: up to $2,000.00. Linked chart rain garden or bioretention: up to $1,500.00. Linked chart infiltration trench or dry well: up to $1,500.00.