Snohomish County Water Quality: 11 Cities Ranked by the Records

Name: Snohomish County Water Quality Data (2026)
Creator: PurityMap
License: https://creativecommons.org/licenses/by/4.0/

Snohomish County, Washington: 11 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my system Open on the map Private wells in Snohomish County

Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

Perfluorohexanesulfonic acid (PFHxS)Detected in 1 system of 11 tested10 ng/L federal MCL (2024) · US EPAHighest4.9 ng/L

ARLINGTON CITY OF4.9 ng/LSample date: 2023-02-23 to 2023-12-21
BOTHELL WATER CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-12-10 to 2025-09-02
EDMONDS CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-09-06 to 2024-06-06
EVERETT PUBLIC WORKS DEPT. CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-02-23 to 2023-11-07
LYNNWOOD CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-10 to 2024-02-06
MARYSVILLE UTILITIESNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-03-22 to 2023-12-12
MONROE WATER SYSTEMNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-31 to 2024-03-19
MOUNTLAKE TERRACE CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-01 to 2024-02-07
SNO PUD 1 - LAKE STEVENSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-01-09 to 2024-10-11
SNOHOMISH CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-01-14 to 2025-10-07
STANWOOD WATER DEPT CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-05-07 to 2024-11-18

Lead (90th percentile)Detected in 5 systems of 6 tested15 µg/L federal action level · US EPAHighest3.5 µg/L

EVERETT PUBLIC WORKS DEPT. CITY OF3.5 µg/LMonitoring period: 2022–2024
SNO PUD 1 - LAKE STEVENS3.2 µg/LMonitoring period: 2022–2024
MARYSVILLE UTILITIES2 µg/LMonitoring period: 2022–2024
STANWOOD WATER DEPT CITY OF1.6 µg/LMonitoring period: 2022–2024
SNOHOMISH CITY OF0.8 µg/LMonitoring period: 2016–2018
ARLINGTON CITY OFNot detectedMonitoring period: 2022–2024

29 substances tested, none detected in any systemShow

Tested in these 11 systems: ARLINGTON CITY OF, BOTHELL WATER CITY OF, EDMONDS CITY OF, EVERETT PUBLIC WORKS DEPT. CITY OF, LYNNWOOD CITY OF, MARYSVILLE UTILITIES, MONROE WATER SYSTEM, MOUNTLAKE TERRACE CITY OF, SNO PUD 1 - LAKE STEVENS, SNOHOMISH CITY OF, STANWOOD WATER DEPT CITY OF

11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
Lithium
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
Perfluoro-3-methoxypropanoic acid (PFMPA)
Perfluoro-4-methoxybutanoic acid (PFMBA)
Perfluorobutanesulfonic acid (PFBS)
Perfluorobutanoic acid (PFBA)
Perfluorodecanoic acid (PFDA)
Perfluorododecanoic acid (PFDoA)
Perfluoroheptanesulfonic acid (PFHpS)
Perfluoroheptanoic acid (PFHpA)
Perfluorohexanoic acid (PFHxA)
Perfluorononanoic acid (PFNA)
Perfluorooctanesulfonic acid (PFOS)
Perfluorooctanoic acid (PFOA)
Perfluoropentanesulfonic acid (PFPeS)
Perfluoropentanoic acid (PFPeA)
Perfluorotetradecanoic acid (PFTA)
Perfluorotridecanoic acid (PFTrDA)
Perfluoroundecanoic acid (PFUnA)

11 cities

Cities ranked by the records

1
LynnwoodLYNNWOOD CITY OF
No PFAS detected
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2
EdmondsEDMONDS CITY OF
No PFAS detected
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3
BothellBOTHELL WATER CITY OF
No PFAS detected
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4
Mountlake TerraceMOUNTLAKE TERRACE CITY OF
No PFAS detected
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5
MonroeMONROE WATER SYSTEM
No PFAS detected
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6
SnohomishSNOHOMISH CITY OF
No PFAS detectedLead below action level
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7
MarysvilleMARYSVILLE UTILITIES
No PFAS detectedLead below action level
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8
StanwoodSTANWOOD WATER DEPT CITY OF
No PFAS detectedLead below action level
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9
EverettEVERETT PUBLIC WORKS DEPT. CITY OF
No PFAS detectedLead below action level
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10
Lake StevensSNO PUD 1 - LAKE STEVENS
No PFAS detectedLead below action level
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11
ArlingtonARLINGTON CITY OF
PFAS detected, within limit
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Showing 6 of 11 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.

PFAS in Snohomish CountyPFAS detected in 1 of 11 cities; none had a sample above a 2024 EPA limit

4.0 ng/L federal MCL · PFOS, ng/LPFAS in Washington

Lead

0of 11 cities above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in Washington

Who supplies the county

Largest water systems

EverettEVERETT PUBLIC WORKS DEPT. CITY OF · WA5324050
215,774 served
MarysvilleMARYSVILLE UTILITIES · WA5351900
88,582 served
LynnwoodLYNNWOOD CITY OF · WA5349270
68,204 served
Lake StevensSNO PUD 1 - LAKE STEVENS · WA5380907
67,710 served
EdmondsEDMONDS CITY OF · WA5322500
34,065 served
BothellBOTHELL WATER CITY OF · WA5307900
33,643 served
ArlingtonARLINGTON CITY OF · WA5302950
29,508 served
Mountlake TerraceMOUNTLAKE TERRACE CITY OF · WA5357250
26,402 served
MonroeMONROE WATER SYSTEM · WA5355820
23,467 served
StanwoodSTANWOOD WATER DEPT CITY OF · WA5383650
17,586 served

Questions

Frequently asked

How does Snohomish County tap water compare across cities?

PurityMap ranks 11 cities in Snohomish County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Lynnwood's main water system: LYNNWOOD CITY OF · PWSID WA5349270 · Purity Score 100 (Excellent) · Confidence: low · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Snohomish County cities had a PFAS sample above a 2024 EPA limit?

None of the 11 Snohomish County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing. PFAS were detected below the limit in 1.

Is there lead in Snohomish County tap water?

Utilities report lead as a 90th-percentile result from home taps. 5 of 11 Snohomish County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

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