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1. Where does the District get its water supply?

The District primarily gets its water supply from groundwater wells located throughout the District. The District is also connected to the regional water system operated by Seattle Public Utilities and managed through a contract with the Cascade Water Alliance.

2. Does the District add anything to my water?

The District currently chlorinates the groundwater for disinfection purposes and to resolve taste and odor issues. State and federal law requires surface water sources, including the water received by Sammamish Plateau Water from the regional system to be disinfected, and chlorine is added to the surface water supply. Fluoride is added to match levels found in the regional water supply to promote dental health.

3. Is the District's water hard or soft?

Water from the District’s groundwater supply is medium hard, and water from the regional water supply is soft. Water hardness refers to the amount of dissolved minerals in the water, primarily calcium and magnesium in the case of hard water, and sodium for treated soft water.

4. How often is my water tested?

In accordance with federal and state regulations, the water throughout the distribution system is tested once every three years. Over 700 samples are taken annually. The Washington Department of Health (DOH) allows us to monitor for some contaminants less than once per year because the concentrations of these contaminants do not change frequently. We take water samples throughout our service area and send them to independent testing laboratories. All test results are reported to the DOH. The District’s water quality meets all federal and state standards.

5. How can I learn more about my drinking water quality?

Read our Annual Drinking Water Reports to learn more about your water quality and find the data monitoring tables and water test results. Follow this link to our Annual Drinking Water Reports.