Issaquah, WA Water Quality Report

Is Issaquah tap water safe? See PFAS and lead contamination levels for Issaquah, Washington. Compare to EPA limits and get filter recommendations.

Quick Answers

Is Issaquah, WA tap water safe to drink? Issaquah, WA water has high PFAS contamination. EPA UCMR5 testing detected a peak level of 600 ppt, significantly above the EPA's 4 ppt enforceable limit. A reverse osmosis or certified PFAS filter is strongly recommended.

What contaminants are in Issaquah, WA water? Top PFAS compounds detected in Issaquah water: PFOS (600 ppt), PFHxS (241 ppt), PFNA (28 ppt). See the full table for all monitored contaminants and comparison to EPA limits.

What filter should I use in Issaquah, WA? Match the filter to what's in Washington water: reverse osmosis handles PFAS, lead, and arsenic together (90%+ removal); pitchers certified to NSF-53 for PFAS like ZeroWater or PUR PLUS cover taps you drink from. A standard Brita pitcher will not remove PFAS.

Issaquah, WA Water Quality Summary

EPA testing has detected PFAS "forever chemicals" in Issaquah, WA drinking water. Recent monitoring found a peak level of 600 ppt across 2 water systems, representing an average of 37.68 ppt across 9 detected compounds. These levels come from individual EPA UCMR 5 water samples (2023-2025). The EPA's 4 ppt limit for PFOA and PFOS is enforced on a running annual average, so a sample above it shows real exposure but is not by itself a violation.

Contamination Level: HIGH – High contamination – multiple PFAS compounds detected at levels significantly above EPA safety thresholds.

Top Detected Compounds

  • PFOS: 600 ppt (exceeds EPA 4 ppt limit for PFOA/PFOS)
  • PFHxS: 241 ppt (exceeds EPA 4 ppt limit for PFOA/PFOS)
  • PFNA: 28 ppt (exceeds EPA 4 ppt limit for PFOA/PFOS)
  • PFHpA: 25.8 ppt (exceeds EPA 4 ppt limit for PFOA/PFOS)
  • PFOA: 21.5 ppt (exceeds EPA 4 ppt limit for PFOA/PFOS)

Lead in Issaquah, WA Water

EPA Lead and Copper Rule testing has recorded 23 lead samples for Issaquah water systems, with a 90th-percentile high of 0.0053 mg/L (within the EPA 0.015 mg/L action level). There is no safe level of lead for children; if your home was built before 1986, a certified NSF/ANSI 53 lead-removal filter is recommended.

EPA Violations in Issaquah, WA

Issaquah public water systems have 34 health-based EPA Safe Drinking Water Act violations on record, including Total Trihalomethanes (TTHM), Haloacetic Acids (HAA5), Total Coliform Rule, Interim Enhanced Surface Water Treatment Rule, Surface Water Treatment Rule. Health-based violations mean a contaminant exceeded its federal limit or required treatment was not applied.

About the Data

These figures come from the EPA's Unregulated Contaminant Monitoring Rule 5 (UCMR5) testing program, 2023-2025. UCMR5 is the most comprehensive national PFAS survey of US drinking water, covering about 10,000 public water systems. Population of Issaquah, WA: approximately 40,051.

ZIP Codes Served

98027, 98029

What Issaquah, Washington Residents Should Do

  1. Enter your exact ZIP code at knowyourexposure.com for address-level data
  2. If anyone in your household is pregnant or under 5, prioritize a certified PFAS filter now and consider a home test kit
  3. For long-term protection, an NSF/ANSI 58 reverse osmosis system removes 94-99% of PFAS
  4. Read the Consumer Confidence Report (CCR) your Washington utility publishes each year