Here is what the EPA's own data shows about tap water in Seattle. According to EPA SDWIS data retrieved July 2026, Seattle is served by 16 active community water systems, together reported to serve about 1,236,044 people.
As of July 2026, EPA records show 31 violations across the community water system(s) serving Seattle, going back to the earliest EPA record. 4 of these are classified by the EPA as health-based (a contaminant recorded above the limit the EPA tracks); the rest are monitoring or reporting violations. Each is listed by system below, with its status.
1,161,961 served · surface water · PWSID WA5377050
Health-based Surface Water Treatment Rule: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 4 times in December 2015. The EPA record for these does not include a measured level. All have since returned to compliance, per EPA records.
King County Water District #20
38,974 served · surface water · PWSID WA5338950
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
King County Water District #125
21,904 served · surface water · PWSID WA5341998
Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between July 2016 and July 2024. All have since returned to compliance, per EPA records.
Skyway Water & Sewer
12,036 served · surface water · PWSID WA5338800
Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in January 2018. All have since returned to compliance, per EPA records.
Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in January 2018. All have since returned to compliance, per EPA records.
Ravenwing Ranch
250 served · groundwater · PWSID WA53AB782
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Pcm Aria Marion Llc
230 served · groundwater · PWSID OH5100212
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Valley Mobile Home Park
120 served · groundwater · PWSID OH4503112
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Cherrywood Mobile Home Manor
120 served · groundwater · PWSID WA5312630
Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in April 2023. All have since returned to compliance, per EPA records.
Monitoring Nitrate: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between January 2020 and January 2022. EPA records do not show all of these as returned to compliance.
Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times between January 2016 and January 2020. All have since returned to compliance, per EPA records.
Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between January 2016 and January 2019. All have since returned to compliance, per EPA records.
Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between January 2016 and January 2019. All have since returned to compliance, per EPA records.
Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2011. All have since returned to compliance, per EPA records.
Country Homes Mobile Park
90 served · groundwater · PWSID ID2290007
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Hidden Village Mhp, Llc
66 served · groundwater · PWSID ID2290004
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Montipark Llc
60 served · groundwater · PWSID IA5300688
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Golf Mhp
60 served · groundwater · PWSID OR4100588
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Hot Springs Court
55 served · groundwater · PWSID 083090312
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Brunswick Hills Mhp
50 served · groundwater · PWSID OH5200012
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
River Village Mhp
40 served · groundwater · PWSID OR4105854
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Majestic Oaks Water System
28 served · groundwater · PWSID WA5355860
As of July 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
What this means
A health-based violation means a contaminant was recorded above the limit the EPA tracks for it. A monitoring or reporting violation means a required test or report was late or missed — not that a contaminant was measured above a limit. “Returned to compliance” means the EPA recorded the issue as resolved.
This page summarizes the EPA's own records and does not assess whether your water is safe to drink. For the most current details, you can verify every record directly with the EPA, and contact your water system with questions.
Source: U.S. EPA Envirofacts SDWIS, retrieved July 2026. Records cover the EPA's full reporting history for these systems. Verify at EPA ECHO.