Issaquah, WA: 8 Violations — 82/100 (2026)
2 ZIP codes · 11 water systems · Updated 2026-06-03
Residents of Issaquah generally live with tap water that beats the WA safety average on key EPA compliance metrics.
How Issaquah Compares
Data: EPA SDWIS Last verified: 2026-06-03
Issaquah Water: The Quick Version
- Your city's water systems recorded 8 violations in the past 5 years.
- Average lead level: 0.001 mg/L.
- Homes built before 1986: 31% — older plumbing may contain lead solder.
- Estimated remediation: $2,100 per household.
- CDC health risk index: 8.82.
Water Systems Serving Issaquah
With 3 utilities splitting service in Issaquah, WA, water accountability is distributed across 11 systems on the federal record.
Overview
We track water quality and home safety data for 2 ZIP codes in Issaquah, Washington (population ~59,265), covering 11 community water systems serving approximately 492,425 people region-wide.
2 of 2 ZIP codes (100%) have recorded EPA violations. All violations are monitoring/reporting type.
Home Safety Score
Average Home Safety Score for Issaquah: B (82/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Issaquah water systems draw from: Groundwater, Surface water.
Lead & Copper
- Average lead level (90th percentile): 0.0010 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 0 ZIP codes
- Zone 3 (Low): 2 ZIP codes
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Lead | Inorganic | 3 | 2 |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 3 | 2 |
| Stage 1 DBP Rule | Treatment Technique | 3 | 2 |
| Surface Water Treatment Rule | Treatment Technique | 3 | 2 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 98027 | B | 4 | 0 | Issaquah Water System |
| 98029 | A | 4 | 0 | Issaquah Water System |
All ZIP Codes in Issaquah
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
CDC Health Data for Issaquah
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Key Contaminants Detected in Issaquah
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
How Old Is Issaquah's Housing Stock?
Housing age data helps assess potential lead pipe and infrastructure risks. Newer housing stock generally means lower plumbing-related contamination risk.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Because Issaquah's housing stock spans a wide range of construction eras, the median build year of 1995 lands in a zone where two distinct risk populations share the same residential market. Homes built before 1986 may have lead-soldered copper plumbing joints — that practice was federally prohibited in 1986 but remained standard until then. The fraction built before 1970 face an additional risk: lead pipes used for service line connections were common before that decade, meaning both the pipe and the solder may be lead-containing in the oldest structures. Residents in mid-century or earlier homes face a different risk environment than neighbors in houses built after 1986, even if they drink from the same utility's supply — and that property-level divergence is what makes the age distribution above more diagnostic than the city-wide median alone.
Most homes in Issaquah were built after 1986, reducing the risk of lead contamination from plumbing. Older homes should still be tested.
Source: U.S. Census Bureau ACS B25034.
Issaquah: Remediation Cost in Perspective
While no remediation project is entirely without cost, the relationship between estimated remediation and property values in Issaquah is notably favorable — the equity share is small enough that the household financial perspective is one of proportionality rather than pressure, and most homeowners can treat it as routine planning rather than a significant financial event.
Remediation costs in Issaquah are relatively low compared to home values. The $1,400–$2,900 estimated range is a small fraction of median property value. Home values are 109% above the Washington average.
Protecting Children from Lead in Issaquah
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
31% — that captures the slice of Issaquah housing dating from before the federal ban on solder containing lead. It pairs with aggregate utility readings that either approach or cross 0.015 mg/L, the benchmark set under the EPA Lead and Copper Rule. Together, the two figures shift one-home reads into a standard household-level confirmation, particularly for families with kids. A certified lead-removal filter is available through retailer-verified channels if a kit returns results that warrant additional measures.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Climate-Related Water Risk for Issaquah
100% of ZIP codes in Issaquah are mapped into FEMA-designated flood zones, and the NFIP records 243 claims reflecting a multi-event flood history. That combination places local flood exposure in the range where water-quality implications deserve at least periodic attention.
Issaquah has a moderate flood history with 243 FEMA claims averaging $23,975 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$2,100</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Issaquah, WA