The project Managing Residential Water Demand for Resilient Communities and Healthy Ecosystems in a Changing Climate modeled future residential demand in the Puget Sound Region across a range of urban growth, water use efficiency, and climate scenarios and evaluated the potential role of water reuse.

Project outputs include a series of three technical white papers, five fact sheets distilling key project findings with stakeholder groups, and a fourth white paper connecting project findings to specific state, regional, and local resilience planning activities. Together, these outputs aim to support coordinated action across sectors to ensure sustainable water use that supports both communities and ecosystems.

The project found that without changes to current practices, residential water demand in the Puget Sound Region could nearly double by 2080—driven primarily by population growth.

However, widespread adoption of water-efficient fixtures and landscaping could limit that increase to just 5-7% above 2020 levels. Indoor efficiency improvements alone could save up to 82,000 million gallons per year, while outdoor savings could contribute an additional 45,000–52,000 million gallons annually.

Climate change is expected to modestly increase demand, especially during hotter, drier summers, but these impacts are small compared to the potential savings from efficiency.

The project also found that while Puget Sound communities produce over 300 million gallons of wastewater each day, less than 5% is currently reused—leaving significant opportunities to expand reclaimed water use where it aligns with local demand.

Finally, the project’s stakeholder fact sheets and resilience planning guidance provide actionable insights tailored to water utilities, planners, policymakers, ecosystem managers, and residents—highlighting where integrated planning and cross-sector collaboration can make the biggest difference.

Photo credit: © UW Climate Impacts Group, aerial support provided by LightHawk.

Project Background

Climate change is shifting the timing and reliability of freshwater availability in the Puget Sound Region—bringing hotter, drier summers, lower summer streamflows, and greater uncertainty for communities and ecosystems. At the same time, the region’s population is expected to grow by nearly five million people by 2080, increasing pressure on water systems. Residential use already accounts for the majority of municipal water demand in the region, highlighting the importance of managing demand as part of a broader climate resilience strategy. This project builds on previous studies, developing (1) new, regionally consistent estimates of current use and future demand incorporating a range of development, water efficiency, and climate change scenarios; (2) an analysis of reclaimed water opportunities; and (3) stakeholder-informed strategies for action. Together, these efforts provide a clearer picture of where and how communities can reduce water demand, diversify supplies, and protect instream flows. By linking water use to land use and growth decisions, the project offers practical tools for integrating water into regional climate resilience planning.

Approach

This project used a combination of data analysis, modeling, and stakeholder engagement to understand how residential water use in the Puget Sound Region might change in the future—and what communities can do to prepare. We started by analyzing current water use patterns across the region, using available datasets to estimate baseline residential demand. We then modeled how demand could change through 2080 under different scenarios, including changes in population, development patterns, climate conditions, and water use efficiency. In parallel, we evaluated where and how reclaimed water could supplement local supplies, drawing on wastewater treatment data, land use, and regulatory considerations. The project results are shared through a series of white papers and stakeholder fact sheets that summarize the data, explain key findings, and highlight potential strategies for resilience. This approach helps regional decision-makers explore tradeoffs and identify water solutions that support both growing communities and healthy ecosystems.

Related Resources

The Climate Impacts Group has developed several resources, publications, and connected projects that may be helpful in this work.

White Paper #1: Water Use Patterns and Sources of DataWhite Paper #2: Planning for Demand: How Growth management, Water Efficiency, and Climate Shape Residential Water Use in the Puget Sound RegionWhite Paper #3: Potential for Reclaimed Water Use Within the Puget Sound RegionWhite Paper #4: Integrating Residential Water Demand and Reuse Opportunities Into Puget Sound Resilience Planning EffortsClimate Resilience Planning Resources for Water SystemsSupporting Climate Resilience for Small and Medium Water SystemsClimate Resilience in WA Water System PlanningPSP Climate GuidancePSP Climate Literature Review