Thurston County, Washington
21 ZIP codes · Avg score 91/100 · Grade A · Updated 2026-06-03
For households in Thurston County, the 21 ZIP codes on record show consistently safe tap water.
How Thurston County Compares
How Thurston County Compares
Thurston County scores 13 points above the Washington state average (78/100) and 23 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Thurston County, Washington
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 11.8 (asthma 11.2%, diabetes 10.3%)
Estimated additional annual cost per homeowner: $3,800, driven primarily by sea_level
Infrastructure: 0.372% avg pipe failure probability, 35% of ZIPs at high risk
Violation History (2021–2025)
↓ Improving trendEPA violation counts by year across Thurston County water systems. Health-based shown in red, total in blue.
Peak year: 2022 with 17 violations. Past 5 years: 32 total (32 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: $3,800
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Thurston County
Remediation costs are relatively manageable for most homeowners in Thurston 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 Thurston 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 Thurston County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | City of Olympia | 113,584 | 22 |
| 2 | Grand Mound | 3,764 | 22 |
| 3 | Carlyon Beach Homeowners | 1,273 | 22 |
| 4 | Boston Harbor | 1,153 | 22 |
| 5 | Black Lake Bible Camp & Conf Ctr | 477 | 22 |
30 total water systems serve Thurston County.
All ZIP Codes in Thurston County
21 ZIP codes tracked in Thurston County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 98556 | Littlerock | 99 | A | 1 | — |
| 2 | 98504 | Olympia | 98 | A | 2 | — |
| 3 | 98505 | Olympia | 98 | A | 2 | — |
| 4 | 98508 | Olympia | 98 | A | 2 | — |
| 5 | 98599 | Olympia | 98 | A | 2 | — |
| 6 | 98509 | Lacey | 96 | A | 0 | — |
| 7 | 98506 | Olympia | 94 | A | 2 | $470K |
| 8 | 98507 | Olympia | 94 | A | 2 | — |
| 9 | 98516 | Olympia | 94 | A | 2 | $528K |
| 10 | 98503 | Lacey | 93 | A | 0 | $408K |
| 11 | 98501 | Olympia | 89 | A | 2 | $485K |
| 12 | 98502 | Olympia | 89 | A | 2 | $497K |
| 13 | 98512 | Olympia | 89 | A | 2 | $439K |
| 14 | 98530 | Bucoda | 89 | A | 2 | $219K |
| 15 | 98540 | East Olympia | 88 | A | 0 | — |
| 16 | 98576 | Rainier | 88 | A | 1 | $400K |
| 17 | 98579 | Rochester | 85 | A | 0 | $406K |
| 18 | 98597 | Yelm | 85 | A | 1 | $423K |
| 19 | 98513 | Olympia | 84 | B | 2 | $443K |
| 20 | 98589 | Tenino | 79 | B | 2 | $409K |
| 21 | 98511 | Tumwater | 77 | B | 8 (7 health) | — |
Recommended Buyer Guides for Thurston County
Retailer arrangements don't shape what appears here — the selection logic is independent, filtered against EPA detections and the federal hazard data on file for this county.
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
Deep Dive Reports
Detailed analysis for Thurston County, Washington
Overview
Thurston County in Washington covers 21 ZIP codes with an average Home Safety Score of A (91/100).
17 of 21 ZIP codes have recorded EPA violations. 7 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.