Washington County, Missouri
8 ZIP codes · Avg score 72/100 · Grade B · Updated 2026-07-19
ZipCheckup grade for Washington: B.
This ZIP looks solid, with a few items worth a quick check.
In current tracking cycles, Washington County - spanning 8 ZIP codes - records above-average water quality outcomes; the county's compliance history over recent years shows few departures from federal standards.
How Washington County Compares
How Washington County Compares
Washington County scores 3 points above the Missouri state average (69/100) and 4 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-07-19
ZIP Code Risk Map
Water Quality Map: Washington County, Missouri
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 16 (asthma 11.1%, diabetes 14.3%)
Estimated additional annual cost per homeowner: $881, driven primarily by flood
Infrastructure: 0.396% avg pipe failure probability, 63% of ZIPs at high risk
58.4% of homes built before 1978 (lead paint era)
Violation History (2022–2025)
→ Stable trendEPA violation counts by year across Washington County water systems. Health-based shown in red, total in blue.
Peak year: 2024 with 4 violations. Past 5 years: 7 total (7 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: $881
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
8,989 housing units in Washington 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 Washington County
Remediation costs are relatively manageable for most homeowners in Washington 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 Washington County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water systems serving Washington County
8 community water systems serving Washington County.
- B
- B
- B
- B
- B
- B
Show all 8 water systems
- C
- B
10 total water systems serve Washington County.
Systems with the most violations in Washington County
3 water systems with recorded EPA violations.
- B
- B
- B
All ZIP Codes in Washington County
8 ZIP codes tracked in Washington County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 63622 | Belgrade | 82 | B | 2 | $105K |
| 2 | 63631 | Caledonia | 82 | B | 2 | $138K |
| 3 | 63660 | Mineral Point | 82 | B | 8 (1 health) | $101K |
| 4 | 63648 | Irondale | 78 | B | 5 | $94K |
| 5 | 63664 | Potosi | 74 | B | 5 | $123K |
| 6 | 63630 | Cadet | 63 | C | 0 | $112K |
| 7 | 63674 | Tiff | 63 | C | 0 | — |
| 8 | 63071 | Richwoods | 53 | D | 0 | $123K |
Recommended Buyer Guides for Washington 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 — 58.4% of homes built before 1978
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Deep Dive Reports
Detailed analysis for Washington County, Missouri
Overview
Washington County in Missouri covers 8 ZIP codes with an average Home Safety Score of B (72/100).
5 of 8 ZIP codes have recorded EPA violations. 1 health-based violation have been documented.
← Back to Missouri 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.