C56/100
Sammamish Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 87,878 residents · Washington
What's In Sammamish's Tap Water?
77
Contaminants Tested
1
Exceed EPA Limits
2
Above EPA Goals
3 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 3.80 mg/L | 1.30 mg/L | Over Limit |
chlorate | 265.00 µg/L | — | Above Goal |
Lead (90th percentile) | 0.002 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2009.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
SAMMAMISH PLATEAU WATER & SEWER
Population Served
79,362
Water Source
Purchased Surface Water
System ID
WA5340900
NE SAMMAMISH SEWER & WATER DISTRICT
Population Served
8,516
Water Source
Groundwater
System ID
WA5375265
Frequently Asked Questions About Sammamish Water
Is Sammamish tap water safe to drink?
Sammamish, Washington tap water receives a grade of C (56/100), which is considered fair. 1 contaminant(s) exceed EPA maximum contaminant levels and 61 violation(s) are on record. Residents should consider using an NSF-certified water filter to reduce contaminant exposure.
What contaminants are in Sammamish's water?
Of the 77 contaminants tested in Sammamish's water supply, the most notable include Copper (90th percentile), Lead (90th percentile), chlorate. 1 contaminant(s) exceed EPA legal limits (MCLs). 3 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Sammamish have any water quality violations?
Yes, Sammamish has 61 EPA violation(s) on record, with the most recent in 2022. Violation types include MR, MCL. 3 of these are health-based violations, which are the most serious category.
Do I need a water filter in Sammamish?
Based on EPA data, using a water filter in Sammamish is recommended. 1 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does Sammamish's tap water come from?
Sammamish's drinking water is sourced from purchased surface water and supplied by SAMMAMISH PLATEAU WATER & SEWER and 1 other water system(s). The system serves approximately 87,878 people. Surface water sources include rivers, lakes, and reservoirs.
How often is Sammamish's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Sammamish's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does Sammamish's water compare to other cities in Washington?
Sammamish's water quality score of 56/100 earns a grade of C, which is considered fair. This is a below-average score that indicates room for improvement. Visit our Washington state page to see how all cities in the state compare.
What should I do if I'm concerned about Sammamish's water quality?
If you have concerns about Sammamish's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (SAMMAMISH PLATEAU WATER & SEWER) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.