Cistern
Capture and store roof runoff
A cistern collects rainwater from your roof in an above-ground tank. Depending on the system, that water can be slowly released or saved for outdoor watering during drier months.
Seattle RainWise - Cisterns & Rain Gardens
RainWise cisterns and rain gardens for eligible Seattle properties.
How RainWise Works
A smarter way to manage Seattle rain
When rain falls on your roof, it usually flows through the gutters and into Seattle’s sewer and drainage systems. During heavy storms, that added water can contribute to flooding, sewer overflows, and pollution in local waterways.
RainWise is a Seattle Public Utilities and King County rebate program that helps eligible property owners manage that water at home. Through the program, homeowners can install cisterns, rain gardens, or a combination of the two—often with most or all of the eligible project cost covered by a rebate.
As a RainWise contractor, BOS can evaluate your property, recommend an appropriate system, complete the installation, and guide the project through the RainWise inspection and rebate process.
Your Options
Cisterns and rain gardens
Rain Garden
Let water soak naturally into the soil
A rain garden directs roof runoff into a landscaped area where the water can temporarily collect and gradually soak into the soil.
Both options can help manage stormwater while adding useful and attractive features to your property.
Eligible Expenses
What the rebate may cover
Eligible RainWise project costs may include:
- Cisterns and standard plumbing materials
- Standard cistern base materials
- Installation and plumbing labor
- Rain garden soil and drainage rock
- Standard rain garden plants
- Rain garden plumbing materials
- Rain garden installation labor
The amount available depends on the property, the roof area being managed, and the system selected. RainWise requires eligible properties to work with a RainWise-trained contractor.
Planning Ahead
Possible additional costs
Some items may not be included in the RainWise rebate, such as:
- Taxes associated with the rebate
- Gutter repairs or modifications outside the approved RainWise scope
- Specialty or upgraded plants and materials
- Additional landscaping or construction requested by the homeowner
BOS will review the proposed project and explain any potential customer costs before work begins.
From Eligibility to Installation
How the process works
- 1
Check your eligibility
Use the RainWise address checker to see whether your property is located in an eligible area.
- 2
Schedule a site visit with BOS
We’ll look at your roof drainage, available space, and possible cistern or rain garden locations.
- 3
Review your project options
We’ll recommend a system and explain the estimated rebate and any costs outside the program.
- 4
Complete the RainWise approval process
BOS prepares the required project information and coordinates the pre-installation review.
- 5
Install your system
Once approved, we complete the cistern, rain garden, or combined installation.
- 6
Complete the final inspection and paperwork
We coordinate the post-installation review and submit the required RainWise documentation.
- 7
Enjoy a yard that works smarter in the rain
Your completed system helps manage stormwater while adding a useful feature to your property.
Take the First Step
Ready to see whether your property qualifies?
Check your eligibility, then contact BOS to schedule a site visit and discuss your RainWise options.
Looking for other exterior or drainage work? Explore all BOS services.
Recent Work
Featured Seattle RainWise - Cisterns & Rain Gardens Projects
Explore a few examples of projects completed by the BOS team.