Lewis County, Washington
22 ZIP codes · Avg score 80/100 · Grade B · Updated 2026-06-03
In current tracking cycles, Lewis County — spanning 22 ZIP codes — records above-average water quality outcomes; the county's compliance history over recent years shows few departures from federal standards.
How Lewis County Compares
How Lewis County Compares
Lewis County scores 2 points above the Washington state average (78/100) and 12 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Lewis County, Washington
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 13.9 (asthma 11.3%, diabetes 12.1%)
Estimated additional annual cost per homeowner: $2,284, driven primarily by sea_level
Infrastructure: 0.417% avg pipe failure probability, 38% of ZIPs at high risk
64.3% of homes built before 1978 (lead paint era)
Violation History (2021–2025)
↓ Improving trendEPA violation counts by year across Lewis County water systems. Health-based shown in red, total in blue.
Peak year: 2021 with 3 violations. Past 5 years: 9 total (9 health-based). Health-based violations are declining versus the prior 2-year window.
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: $2,284
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
36,445 housing units in Lewis 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 Lewis County
Remediation costs are relatively manageable for most homeowners in Lewis 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 Lewis 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 Lewis County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Boistfort Valley | 2,389 | 27 |
| 2 | Centralia Public Works - Water | 28,164 | 16 |
| 3 | Chehalis Water Department | 11,426 | 16 |
| 4 | Newaukum Hill Water Assn | 493 | 16 |
| 5 | Grand Mound | 3,764 | 11 |
33 total water systems serve Lewis County.
All ZIP Codes in Lewis County
22 ZIP codes tracked in Lewis County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 98522 | Adna | 95 | A | 0 | — |
| 2 | 98565 | Napavine | 95 | A | 3 | $276K |
| 3 | 98570 | Onalaska | 95 | A | 0 | $352K |
| 4 | 98596 | Winlock | 95 | A | 1 | $365K |
| 5 | 98564 | Mossyrock | 94 | A | 9 (1 health) | $214K |
| 6 | 98304 | Ashford | 90 | A | 0 | $241K |
| 7 | 98572 | Pe Ell | 90 | A | 10 (2 health) | $218K |
| 8 | 98591 | Toledo | 90 | A | 1 | $405K |
| 9 | 98356 | Morton | 87 | A | 4 | $281K |
| 10 | 98377 | Randle | 85 | A | 0 | $425K |
| 11 | 98361 | Packwood | 83 | B | 4 | $266K |
| 12 | 98531 | Centralia | 75 | B | 11 | $286K |
| 13 | 98532 | Chehalis | 75 | B | 5 | $382K |
| 14 | 98542 | Ethel | 73 | B | 0 | $416K |
| 15 | 98585 | Silver Creek | 73 | B | 0 | $376K |
| 16 | 98593 | Vader | 73 | B | 0 | $338K |
| 17 | 98336 | Glenoma | 66 | C | 0 | $245K |
| 18 | 98533 | Cinebar | 66 | C | 0 | $352K |
| 19 | 98539 | Doty | 66 | C | 0 | — |
| 20 | 98538 | Curtis | 65 | C | 0 | $398K |
| 21 | 98544 | Galvin | 65 | C | 0 | — |
| 22 | 98582 | Salkum | 62 | C | 5 | — |
Recommended Buyer Guides for Lewis County
Below: editorial picks, no sponsored placements.
- Best Water Filters for Lead — Lead above EPA action level in 1 ZIP code
- Best Lead Paint Test Kits — 64.3% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
Deep Dive Reports
Detailed analysis for Lewis County, Washington
Overview
Lewis County in Washington covers 22 ZIP codes with an average Home Safety Score of B (80/100).
10 of 22 ZIP codes have recorded EPA violations. 3 health-based violations have been documented.
← 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.