Washtenaw County Water Quality: 2 Cities Ranked by the Records
Washtenaw County, Michigan: 2 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
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.
Water hardnessDetected in 1 systemAesthetic, no federal health limit · USGSHighest7.4 gpg
- ANN ARBOR7.4 gpgReporting year: 2025
Lead (90th percentile)Detected in 2 systems15 µg/L federal action level · US EPAHighest4.1 µg/L
- YPSILANTI COMMUNITY UTILITY AUTHORITY4.1 µg/LMonitoring period: 2025–2025
- ANN ARBOR2.3 µg/LMonitoring period: 2021–2023
Perfluorohexanoic acid (PFHxA)Detected in 1 system of 2 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest3.5 ng/L
- ANN ARBOR3.5 ng/LSample date: 2023-03-16 to 2023-12-18
- YPSILANTI COMMUNITY UTILITY AUTHORITYNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-08-06 to 2025-05-13
Perfluorobutanoic acid (PFBA)Detected in 1 system of 2 testedNo federal or state limit; shown for transparencyHighest6.1 ng/L
- ANN ARBOR6.1 ng/LSample date: 2023-03-16 to 2023-12-18
- YPSILANTI COMMUNITY UTILITY AUTHORITYNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-08-06 to 2025-05-13
Perfluoropentanoic acid (PFPeA)Detected in 1 system of 2 testedNo federal or state limit; shown for transparencyHighest4.7 ng/L
- ANN ARBOR4.7 ng/LSample date: 2023-03-16 to 2023-12-18
- YPSILANTI COMMUNITY UTILITY AUTHORITYNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-08-06 to 2025-05-13
27 substances tested, none detected in any systemShow
Tested in these 2 systems: ANN ARBOR, YPSILANTI COMMUNITY UTILITY AUTHORITY
- 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)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorohexanesulfonic acid (PFHxS)
- Perfluorononanoic acid (PFNA)
- Perfluorooctanesulfonic acid (PFOS)
- Perfluorooctanoic acid (PFOA)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
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.
0of 2 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 Michigan1city reports hardness · Ann Arbor, 7.4 gpg
Hard on the USGS scale. An aesthetic measure with no federal health limit.
Hard water explainedLargest water systems
Frequently asked
How does Washtenaw County tap water compare across cities?
PurityMap ranks 2 cities in Washtenaw 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 Ann Arbor's main water system: ANN ARBOR · PWSID MI0000220 · Purity Score 97 (Excellent) · Confidence: moderate · 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 Washtenaw County cities had a PFAS sample above a 2024 EPA limit?
None of the 2 Washtenaw 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 Washtenaw County tap water?
Utilities report lead as a 90th-percentile result from home taps. 2 of 2 Washtenaw 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.
Does Washtenaw County have hard water?
Hardness is published in utility water-quality reports for 1 Washtenaw County city on record; the hardest is Ann Arbor at 7.4 grains per gallon. Hardness affects scale and appliances; it is not a health finding.
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