Mason County, Washington
9 ZIP codes · Avg score 92/100 · Grade A · Updated 2026-07-16
ZipCheckup grade for Mason: A.
No federal data flags a major home-safety concern for this ZIP.
Throughout Mason County, the 9 monitored ZIP codes show low violation rates and healthy safety scores - a pattern that puts the county well above the state baseline for drinking water quality.
How Mason County Compares
How Mason County Compares
Mason County scores 14 points above the Washington state average (78/100) and 24 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-07-16
ZIP Code Risk Map
Water Quality Map: Mason County, Washington
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 13.7 (asthma 11.1%, diabetes 12.2%)
Estimated additional annual cost per homeowner: $3,603, driven primarily by sea_level
Infrastructure: 0.291% avg pipe failure probability, 11% of ZIPs at high risk
46.1% 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: $3,603
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
32,352 housing units in Mason 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 Mason County
Remediation costs are relatively manageable for most homeowners in Mason 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 Mason County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water systems serving Mason County
8 community water systems serving Mason County.
- A
- A
- A
- A
- A
- A
Show all 8 water systems
- A
- A
32 total water systems serve Mason County.
Systems with the most violations in Mason County
4 water systems with recorded EPA violations.
- A
- A
- A
- A
All ZIP Codes in Mason County
9 ZIP codes tracked in Mason County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 98546 | Grapeview | 95 | A | 0 | $482K |
| 2 | 98548 | Hoodsport | 95 | A | 1 | $255K |
| 3 | 98555 | Lilliwaup | 95 | A | 0 | — |
| 4 | 98524 | Allyn | 94 | A | 2 | $513K |
| 5 | 98228 | Bellingham | 93 | A | 2 | — |
| 6 | 98588 | Tahuya | 90 | A | 0 | $325K |
| 7 | 98592 | Union | 90 | A | 0 | $521K |
| 8 | 98528 | Belfair | 89 | A | 2 | $367K |
| 9 | 98584 | Shelton | 85 | A | 0 | $365K |
Recommended Buyer Guides for Mason County
Editorial methodology pairs each documented risk in this county with the buyer category that addresses it, drawing on water-quality detections, housing-stock lead exposure, EPA Radon Zone designation, and FEMA flood and wildfire ratings. NSF-certified options surface where applicable, and products that match the specific contaminant take priority.
- Best Water Testing Kits — Baseline water quality check for your ZIP
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant peace of mind
Deep Dive Reports
Detailed analysis for Mason County, Washington
Overview
Mason County in Washington covers 9 ZIP codes with an average Home Safety Score of A (92/100).
4 of 9 ZIP codes have recorded EPA violations. All violations are monitoring/reporting type.
← Back to Washington 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.