Mercer County, Ohio
8 ZIP codes · Avg score 54/100 · Grade D · Updated 2026-06-03
State safety rankings put Mercer County near the bottom — 8 ZIP codes, below-average compliance.
How Mercer County Compares
How Mercer County Compares
Mercer County scores 6 points below the Ohio state average (60/100) and 14 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Mercer County, Ohio
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 13.8 (asthma 10.4%, diabetes 12.1%)
Estimated additional annual cost per homeowner: $1,253, driven primarily by energy_code_gap
Infrastructure: 0.404% avg pipe failure probability, 38% of ZIPs at high risk
72.3% of homes built before 1978 (lead paint era)
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: $1,253
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
16,093 housing units in Mercer 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 Mercer County
Remediation costs are relatively manageable for most homeowners in Mercer 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 Mercer 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 Mercer County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | ROCKFORD VILLAGE | 1,120 | 8 |
| 2 | Coldwater Village | 4,774 | 3 |
| 3 | Celina City | 11,682 | 2 |
| 4 | Grand Lake Estates | 103 | 2 |
| 5 | Saint Charles Center | 142 | 2 |
7 total water systems serve Mercer County.
All ZIP Codes in Mercer County
8 ZIP codes tracked in Mercer County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 45828 | Coldwater | 70 | B | 1 | $234K |
| 2 | 45882 | Rockford | 63 | C | 8 | $158K |
| 3 | 45822 | Celina | 58 | C | 2 | $185K |
| 4 | 45826 | Chickasaw | 55 | C | 1 | $275K |
| 5 | 45862 | Mendon | 53 | D | 0 | $112K |
| 6 | 45866 | Montezuma | 53 | D | 0 | $113K |
| 7 | 45860 | Maria Stein | 40 | D | 0 | $300K |
| 8 | 45883 | Saint Henry | 40 | D | 0 | $283K |
Recommended Buyer Guides for Mercer County
Strictly editorial — no paid placements influence which guides appear; the selection draws on NSF certifications and EPA detection records for water systems serving this county.
- Best Lead Paint Test Kits — 72.3% of homes built before 1978
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
Deep Dive Reports
Detailed analysis for Mercer County, Ohio
Overview
Mercer County in Ohio covers 8 ZIP codes with an average Home Safety Score of D (54/100).
4 of 8 ZIP codes have recorded EPA violations. All violations are monitoring/reporting type.
← Back to Ohio 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.
What You Can Do
Mercer County has a grade of D. Here are steps to protect your household.
Test your tap water
Order a certified lab test kit ($20-$50) to check for lead, bacteria, and other contaminants specific to your ZIP code.
Consider a certified water filter
NSF-certified filters can remove most common contaminants. Match the filter to your test results for best protection. Try our filter matcher
Contact your water utility
Request the latest Consumer Confidence Report (CCR) from your water provider. It details exactly what was found in your water supply.
Check for lead in your home
72.3% of homes in this county were built before 1978. Older plumbing and solder can leach lead into drinking water, especially in the morning.