Community Water System · PWS MI0001370
Chelsea
Chelsea, Michigan 48118 - drinking water served from groundwater sources to 5,474 people, tracked in EPA SDWIS and UCMR5.
- 5,474
- People served
- 24
- EPA violations
- 16
- Health-based
- No PFAS
- UCMR5 result
The verdict
EPA records 24 drinking-water violations at Chelsea, 67% of them health-based - above the Michigan per-system average.
- 24
- Total EPA violations on record
- 67%
- Health-based (MCL / treatment failure)
- 5,474
- People served by this system
- 0
- PFAS compounds detected (UCMR5)
Water Quality Snapshot: Chelsea
Chelsea is a local-owned community water system that delivers drinking water to 5,474 residents in Chelsea, Michigan (Washtenaw County) through 2,000 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 24 total violations for this system , of which 16 (67%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. The most recent violation on record dates to 2005.
The most frequently cited contaminant at this system is Coliform (TCR), recorded in 12 violations (MCL, health-based). This system was sampled under EPA's UCMR5 PFAS monitoring program and no PFAS compounds were detected above the minimum reporting level.
Across Michigan, EPA tracks 10,959 public water systems serving 9,098,093 people, with 255,201 cumulative violations and 31,467 health-based violations on record. About 86% of systems in the state carry at least one violation, and state-wide the average per system is 23.3 violations. Statewide, 87 of 318 UCMR5-tested systems have reported PFAS detections (27.4%).
Chelsea's 24 violations sit above the Michigan average.
All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 2,000
- County
- Washtenaw
- School/Daycare
- No
- MCL Violations
- 12
- Monitoring Violations
- 0
- Treatment Tech Violations
- 4
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 12 | 1996 |
| Acrylamide | TT | 4 | 2003 |
| Consumer Confidence Rule | Other | 3 | 2005 |
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 58 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFHxS | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 7/14/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHxA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 7/14/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| 9Cl-PF3ONS | 7/14/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFNA | 7/14/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFUnA | 7/14/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHpA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBA | 7/14/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 7/14/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFOS | 7/14/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 7/14/2025 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFMBA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| ADONA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 7/14/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFTA | 7/14/2025 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFTrDA | 7/14/2025 | <7.00 ppt | 7.00 ppt | Not Detected |
| NEtFOSAA | 7/14/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFPeA | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 7/14/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 7/14/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 6:2 FTS | 7/14/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 7/14/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 7/14/2025 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFHxA | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 1/13/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOS | 1/13/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOA | 1/13/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFTA | 1/13/2025 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFDoA | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 1/13/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 1/13/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 1/13/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 9Cl-PF3ONS | 1/13/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| ADONA | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 1/13/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 1/13/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 6:2 FTS | 1/13/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 1/13/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
Verify This Water System
The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Chelsea.
EPA SDWIS, Federal Reports
EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:
View PWS ID MI0001370 on SDWISSource: EPA SDWIS Federal Reports Search
Michigan Drinking Water Authority
Michigan EGLE, Drinking Water and Environmental Health Division is the primacy agency that licenses and inspects Chelsea under EPA-delegated authority.
Open MI regulator portalSource: Michigan EGLE, Drinking Water and Environmental Health Division
Violation Timeline
Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.
| Year (latest) | Contaminant | Category | Count | EPA Record |
|---|---|---|---|---|
| 2005 | Consumer Confidence Rule | Other | 3 | SDWIS / MI0001370 / 7000 |
| 2003 | Acrylamide | TT | 4 | SDWIS / MI0001370 / 2265 |
| 1996 | Coliform (TCR) | MCL | 12 | SDWIS / MI0001370 / 3100 |
How Chelsea Compares
Cross-reference this system's record against state averages and the federal MCL framework for context.
| Metric | Chelsea | Michigan avg | Federal benchmark |
|---|---|---|---|
| Total violations | 24 | 23.3 | SDWA compliance, any non-zero count is a recorded breach |
| Health-based violations | 16 | 2.9 | Indicates a contaminant exceeded a federal MCL |
| PFAS detection | None | 27.4% | EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt |
| Population served | 5,474 | 830 | Sizing context for compliance burden |
Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 10,959 regulated public water systems in Michigan.
Federal MCL reference, Safe Drinking Water Act thresholds ▼
| Contaminant | Federal MCL / Action Level | Note |
|---|---|---|
| Lead | 0 mg/L (Action Level: 0.015 mg/L) | Lead and Copper Rule treatment technique |
| Arsenic | 0.010 mg/L (10 ppb) | Health-based MCL since 2006 |
| Total Coliform | Treatment technique (RTCR) | Indicator organism, monitoring trigger |
| PFOA / PFOS (PFAS) | 4.0 ppt each (final 2024 rule) | Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026) |
| Nitrate (as N) | 10 mg/L | Acute health risk for infants |
Frequently Asked Questions
Is Chelsea water safe to drink? ▼
How many people does Chelsea serve? ▼
What type of violations does Chelsea have? ▼
Has PFAS been detected in Chelsea water? ▼
What water source does Chelsea use? ▼
Where does this data come from? ▼
Read our methodology - how this data is sourced, computed, and verified.
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.