Water Supply

Photo of watershed on a clear morning
The Masonry Pool and Masonry Dam at the Cedar River Watershed

The Water System Plan (WSP) provides direction for managing and operating the water system that serves both Seattle and a number of nearby cities and water districts. This plan describes how Seattle Public Utilities (SPU) meets current and future water demands, maintains the system and meets water quality regulations.

Seattle Public Utilities prepares the WSP under regulations adopted by the Washington Department of Health for public drinking water suppliers. The plan must also be compatible and consistent with local and regional land use plans and meet the capital facility planning requirements of the Growth Management Act.

The 2019 Water System Plan articulates SPU's commitment to:

  • Ensuring a long-term, high-quality water supply while protecting the environment and fishery resources
  • Using asset management principles in business decisions to provide the highest value to ratepayers over the long-term
  • Continuing to be a leader in water conservation
  • Being customer-driven
  • Working together with other water providers and regional jurisdictions to address water issues.

Learn more about SPU's Water System Plan.



Seattle Public Utilities sells water to its wholesale water customers under the terms of wholesale contracts. View current wholesale customer rates.


Current Conditions

Seattle Public Utilities supplies water to 1.5 million people and businesses in the region. Nearly all this water is from the 90,000-acre Cedar River Watershed and the 13,300-acre South Fork Tolt River Watershed in eastern King County. Our operations must be protective of the environment, particularly the fish and wildlife resources of the Cedar and Tolt River watersheds, while we provide a reliable source of high quality drinking water. View current water supply conditions and outlook.


Water Shortage Contingency Plan

Seattle Public Utilities (SPU) has a Water Shortage Contingency Plan which provides guidelines for SPU to manage water supply and demand in the event of a supply disruption. Learn more about the Water Shortage Contingency Plan.