Ontario, CA Water Quality Report

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

Quick Answers

Is Ontario tap water safe to drink? Ontario tap water meets most federal EPA limits, but PFAS compounds have been detected at an average of 0.9 ppt across 8 compounds. A certified pitcher filter or reverse osmosis system is recommended for sensitive populations.

What contaminants are in Ontario water? Top PFAS compounds detected in Ontario water: lithium (16 ppt), PFOA (0.03 ppt), PFPeA (0.01 ppt). See the full table for all monitored contaminants and comparison to EPA limits.

What filter should I use in Ontario? 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.

Ontario Water Quality Summary

EPA testing has detected PFAS "forever chemicals" in Ontario drinking water. Recent monitoring found a peak level of 16 ppt across 3 water systems, representing an average of 0.9 ppt across 8 detected compounds.

Contamination Level: LOW – Low contamination – PFAS detected but at lower levels; monitoring continues.

Top Detected Compounds

  • lithium: 16 ppt (exceeds EPA 4 ppt limit for PFOA/PFOS)
  • PFOA: 0.03 ppt
  • PFPeA: 0.01 ppt
  • PFBA: 0.01 ppt
  • PFHxS: 0.01 ppt

Lead in Ontario Water

EPA Lead and Copper Rule testing has recorded 22 lead samples for Ontario water systems, with a 90th-percentile high of 0.005 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 Ontario

Ontario public water systems have 34 health-based EPA Safe Drinking Water Act violations on record, including 3001, Haloacetic Acids (HAA5), Nitrate, Arsenic, Total Trihalomethanes (TTHMs). 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 Ontario: approximately 175,265.

ZIP Codes Served

91758, 91761, 91762, 91764

What Ontario 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