Washtenaw County, Michigan
21 ZIP codes · Avg score 60/100 · Grade C · Updated 2026-06-04
Current EPA records place Washtenaw County in the middle tier for drinking water safety, with 21 ZIP codes showing a range of outcomes.
How Washtenaw County Compares
How Washtenaw County Compares
Washtenaw County scores 14 points below the Michigan state average (74/100) and 8 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
ZIP Code Risk Map
Water Quality Map: Washtenaw County, Michigan
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 10.6 (asthma 10.6%, diabetes 8.9%)
Estimated additional annual cost per homeowner: $1,283, driven primarily by sea_level
Infrastructure: 0.356% avg pipe failure probability, 20% of ZIPs at high risk
59.1% of homes built before 1978 (lead paint era)
Violation History (2022–2024)
→ Stable trendEPA violation counts by year across Washtenaw County water systems. Health-based shown in red, total in blue.
Peak year: 2023 with 7 violations. Past 5 years: 13 total (13 health-based).
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $1,283
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
157,909 housing units in Washtenaw County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Washtenaw County
Remediation costs are relatively manageable for most homeowners in Washtenaw County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Washtenaw County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Washtenaw County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Pittsfield Township | 24,500 | 63 |
| 2 | Loch Alpine Sanitary Authority | 1,506 | 63 |
| 3 | Ann Arbor | 241,868 | 56 |
| 4 | Scio Township | 8,500 | 56 |
| 5 | Ann Arbor Township | 1,338 | 56 |
30 total water systems serve Washtenaw County.
All ZIP Codes in Washtenaw County
21 ZIP codes tracked in Washtenaw County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 48176 | Saline | 69 | C | 2 | $385K |
| 2 | 48198 | Ypsilanti | 69 | C | 5 (1 health) | $178K |
| 3 | 48130 | Dexter | 66 | C | 0 | $453K |
| 4 | 48158 | Manchester | 66 | C | 0 | $298K |
| 5 | 48105 | Ann Arbor | 65 | C | 7 | $486K |
| 6 | 48108 | Ann Arbor | 65 | C | 7 | $378K |
| 7 | 48190 | Whittaker | 65 | C | 2 | $220K |
| 8 | 48189 | Whitmore Lake | 64 | C | 7 (1 health) | $286K |
| 9 | 48197 | Ypsilanti | 64 | C | 5 (1 health) | $274K |
| 10 | 48106 | Ann Arbor | 61 | C | 7 | — |
| 11 | 48107 | Ann Arbor | 61 | C | 7 | — |
| 12 | 48109 | Ann Arbor | 61 | C | 7 | — |
| 13 | 48113 | Ann Arbor | 61 | C | 7 | — |
| 14 | 48103 | Ann Arbor | 60 | C | 7 | $455K |
| 15 | 48104 | Ann Arbor | 60 | C | 7 | $482K |
| 16 | 48118 | Chelsea | 57 | C | 7 (4 health) | $349K |
| 17 | 48025 | Franklin | 53 | D | 0 | $515K |
| 18 | 48139 | Hamburg | 53 | D | 0 | $177K |
| 19 | 48143 | Lakeland | 53 | D | 0 | — |
| 20 | 48191 | Willis | 53 | D | 0 | $276K |
| 21 | 48115 | Bridgewater | 40 | D | 0 | — |
Recommended Buyer Guides for Washtenaw County
Methodologically, the recommendation order reflects severity in the federal record: contaminants flagged in EPA detection records for this county outrank generic water concerns, FEMA-confirmed hazard ratings shift emergency-related categories upward, and CDC lead-exposure markers govern when lead-test kits and certified filters appear at the top of the list.
- Best Lead Paint Test Kits — 59.1% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
Deep Dive Reports
Detailed analysis for Washtenaw County, Michigan
Overview
Washtenaw County in Michigan covers 21 ZIP codes with an average Home Safety Score of C (60/100).
14 of 21 ZIP codes have recorded EPA violations. 7 health-based violations have been documented.
← Back to Michigan water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.