Sammamish, WA Tap Water Quality

Tap water in Sammamish, WA ranks among the best in the state, maintaining a remarkable average water quality score of 88/100 across its 2 ZIP codes. Based on recent EPA Safe Drinking Water Act compliance records, water provided by Sammamish Plateau Water & Sewer and other municipal suppliers has consistently met or exceeded federal safety standards. This top-tier "A" grade reflects strong infrastructure, diligent monitoring by Washington State Department of Health, and low contaminant levels.

A major factor in Sammamish's high rating is its flawless health-based violation record. Over the past 5 years of EPA tracking, local water systems have recorded zero health-based violations. This means that regulated contaminants—such as lead, arsenic, and harmful bacteria—have not exceeded the Maximum Contaminant Levels (MCLs) allowed by federal law. Drawing primarily from surface water, the city utilizes advanced filtration to maintain this standard.

Fortunately, the modeled risk for widespread lead exposure in Sammamish's municipal water is relatively low compared to national averages. However, because lead typically enters drinking water through the corrosion of older, individual home plumbing rather than the main supply lines, residents in homes built before 1986 should still exercise caution by running the tap before use.