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 tap water safe to drink? Issaquah 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 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? Reverse osmosis removes 90%+ of PFAS, lead, and arsenic. NSF-53 certified pitcher and faucet filters (ZeroWater, Clearly Filtered, LifeStraw) work for smaller households. Skip standard Brita filters for PFAS removal.

Issaquah Water Quality Summary

EPA testing has detected PFAS "forever chemicals" in Issaquah drinking water. Recent monitoring found a peak level of 600 ppt across 2 water systems, representing an average of 32.73 ppt across 9 detected compounds.

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 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

Issaquah public water systems have 34 health-based EPA Safe Drinking Water Act violations on record, including Haloacetic Acids (HAA5), Nitrate, Arsenic, Total Trihalomethanes (TTHMs), Gross Alpha (excl. radon & uranium). 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 drinking water survey in US history, covering 66,000+ public water systems. Population of Issaquah: approximately 40,051.

ZIP Codes Served

98027, 98029

What Issaquah Residents Should Do

  1. Enter your exact ZIP code at knowyourexposure.com for address-level data
  2. Install an NSF/ANSI 58 reverse osmosis filter (removes 94-99% of PFAS)
  3. If you're in a high-exposure group (pregnant, young children), consider a PFAS home test kit
  4. Review your utility's Consumer Confidence Report (CCR) annually