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Tap water quality report

Sammamish, WA

EPA monitoring detected 26 contaminants across the 2 water suppliers serving Sammamish. A detection doesn't automatically mean the water is unsafe — see the level at the main supplier for each below, with its EPA source and period.

2
water suppliers
89,064
people served
26
contaminants found
Washington rankings Lead in Washington PFAS in Washington

What was found in Sammamish's water

The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.

ContaminantLevel vs EPA limitSuppliersSource
Nitrate
2233.5 µg/L 22%
of the EPA limit 10000 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Nitrate-Nitrite
1728.4999999999998 µg/L 17%
of the EPA limit 10000 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2018
2/2 SYR4
Fluoride
800 µg/L 20%
of the EPA limit 4000 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2018
1/2 SYR4
TTHM
45.30999999999999 µg/L 57%
of the EPA limit 80 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Chloroform
41.47499999999999 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Total Haloacetic Acids (HAA5)
38.38199999999999 µg/L 64%
of the EPA limit 60 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Copper
30.9 µg/L 2.4%
of the EPA limit 1300 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2018
1/2 SYR4
Trichloroacetic Acid
22.109999999999996 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Dichloroacetic Acid
17.969999999999995 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
1/2 SYR4
Arsenic
6.39 µg/L 64%
of the EPA limit 10 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2018
Highest in the city: 6.7 µg/L — NE SAMMAMISH SEWER & WATER DISTRICT · 9,702 people · 2019
2/2 SYR4
Lead
3.9 µg/L 26%
of the EPA limit 15 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2018
1/2 SYR4
Bromodichloromethane
3.7 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Monochloroacetic Acid
3.2955 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
1/2 SYR4
Dibromochloromethane
1.9819999999999998 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Dibromoacetic Acid
0.6603 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Bromoform
0.6475 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2019
2/2 SYR4
Combined Radium (-226 And -228)
0.5000 pCi/L 10%
of the EPA limit 5 pCi/L
Highest in the city: NE SAMMAMISH SEWER & WATER DISTRICT · 9,702 people · 2012
1/2 SYR4
Cadmium
0.2000 µg/L 4%
of the EPA limit 5 µg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2018
1/2 SYR4
Asbestos
0.1150 MFL 1.6%
of the EPA limit 7 MFL
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2017
1/2 SYR4
PFHXS
0.0165 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2024
1/2 UCMR-5
PFOS
0.0111 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2024
1/2 UCMR-5
PFBS
0.0088 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2024
1/2 UCMR-5
Pfhxa
0.0043 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2024
1/2 UCMR-5
Pfpes
0.0041 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2024
1/2 UCMR-5
Pfpea
0.0039 µg/L
No EPA limit set
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2024
1/2 UCMR-5
Lead
0.0017 mg/L 11%
of the EPA limit 0.0150 mg/L
Main supplier: SAMMAMISH PLATEAU WATER & SEWER · 79,362 people · 2025
2/2 LCR
Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of the system's samples — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving Sammamish

SupplierPopulation served
SAMMAMISH PLATEAU WATER & SEWER 79,362
NE SAMMAMISH SEWER & WATER DISTRICT 9,702

Frequently asked questions about Sammamish tap water

Is Sammamish tap water safe to drink?

EPA testing detected 26 contaminants in the water serving Sammamish. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve Sammamish?

2 public water suppliers report drinking-water monitoring for Sammamish, Washington to the EPA. Each is listed above with its population served.

What contaminants are in Sammamish's water?

The contaminants EPA monitoring detected in Sammamish include Nitrate, Nitrate-Nitrite, Fluoride, TTHM, Chloroform. The full list, with the level at the main supplier and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.