ONTARIO is served by 1 water provider on file with the EPA.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
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Results for ONTARIO, CA
1 water provider on file serving this city.
Quick answer: ONTARIO's water has no violations on file and no single reading stands out against its peers (1 other providers in this area). It serves roughly 185,010 people, and the full breakdown below reflects everything EPA and California have on record for it.
Lead Summary
PFBA
PFOA
PFPEA
PFHXA
PFOS
PFHXS
Totalhaloaceticacids (HAA5)
TTHM
Chloroform
Bromodichloromethane
Dibromochloromethane
Bromoform
Dichloroaceticacid
Trichloroaceticacid
Dibromoaceticacid
Nitrate
Perchlorate
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.0006 mg/L (ppm)
12/31/2024
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 15 UG/L (ppb)
5/8/2025
TTHM
Detected: 38 UG/L (ppb)
8/14/2025
A group of disinfection byproducts formed when chlorine reacts with organic matter. Long-term exposure above the legal limit has been linked to increased cancer risk in some studies.
Chloroform
Detected: 8.8 UG/L (ppb)
8/14/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 13 UG/L (ppb)
8/14/2025
Dibromochloromethane
Detected: 12 UG/L (ppb)
8/14/2025
Bromoform
Detected: 5.1 UG/L (ppb)
8/14/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate
Detected: 3.9 MG/L (ppm)
10/16/2025
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
PFBA
Detected: 0.0064 µg/L (ppb)
2/15/2023
PFOA
Detected: 0.03 µg/L (ppb)
2/28/2023
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFPEA
Detected: 0.0048 µg/L (ppb)
8/9/2023
PFHXA
Detected: 0.0071 µg/L (ppb)
2/15/2023
PFOS
Detected: 0.0052 µg/L (ppb)
2/15/2023
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFHXS
Detected: 0.0042 µg/L (ppb)
2/15/2023
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 5.6 UG/L (ppb)
5/8/2025
Trichloroaceticacid
Detected: 6.4 UG/L (ppb)
5/8/2025
Dibromoaceticacid
Detected: 2.8 UG/L (ppb)
5/8/2025
Perchlorate
Detected: 1.1 UG/L (ppb)
10/1/2025
Can occur naturally or from industrial/military sources; may interfere with thyroid function at elevated levels.
Filtration considerations: General system types, not a specific product recommendation.