Community Water System · PWS WA5377050
Seattle Public Utilities
Operator location Seattle, Washington - larger served population (> 3,309) at 1,091,904 people served; 29 SDWIS violations on record from surface water sources.
- 1,091,904
- People served (this PWS)
- 29
- EPA violations (this PWS)
- 4
- Health-based (this PWS)
- No PFAS
- UCMR5 (this PWS)
Seattle Public Utilities standing, mid SDWIS violation third
1,091,904 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 14% is middle-third health share (≤ 23%). UCMR5: UCMR5 tested, none detected. Population rank #24 of 29,740 among systems serving 500+.
The verdict
Seattle Public Utilities lands in the middle third by violation volume (29), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is large (1,091,904; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 14% (middle-third health share (≤ 23%)). UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #24 of 29,740
- Population · /systems
- #1 of 766
- Population · WA
- 29
- Total EPA violations on record
- 14%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 171,515
- County
- King
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 25
- Treatment Tech Violations
- 4
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Nitrate | MR | 24 | 2007 |
| Surface Water Treatment Rule | TT | 2 | 2015 |
| Lead and Copper Rule | TT | 2 | 1995 |
| Gross Alpha, Excl. Radon and U | MR | 1 | 1979 |
Violation Count vs. the National Corpus
Seattle Public Utilities has 29 recorded EPA violations, 41% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 58% carry more. 14% of this system's own violations are health-based (4 of 29), and it ranks #24 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
29 Lower than most fewer violations than 58% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 232 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| NMeFOSAA | 9/18/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFTrDA | 9/18/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 9/18/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| NEtFOSAA | 9/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFEESA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 7/18/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 7/18/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| 9Cl-PF3ONS | 7/18/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| NFDHA | 7/18/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFPeS | 7/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpS | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 7/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHxA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| ADONA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 7/18/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFTA | 7/18/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFDoA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 7/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 7/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 7/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHpS | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 7/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTA | 7/18/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFPeS | 7/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFMBA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBA | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFDA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 7/18/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| HFPO-DA | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 7/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 7/18/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 7/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
Population served record for Seattle Public Utilities
EPA SDWIS lists 1,091,904 people served and 171,515 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS · Washington State Department of Health, Office of Drinking Water
Nationwide peers
29 violations · 1,091,904 served: nearest cross-state SDWIS matches.
Cross-state systems near this violation count
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Seattle Public Utilities
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Washington compares on the same EPA violation measures. Washington systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.