Ontario, California Tap Water Quality Report
Serving utility: Chino Basin Desalter Authority - Desalter 2
Updated March 2026 • Data from EWG Tap Water Database & EPA SDWIS
Notable Concerns
Ontario tap water has 4 contaminants exceeding EWG health guidelines, including Perfluorohexane sulfonate (PFHXS), Arsenic, Nitrate. Additionally, 5 known or suspected carcinogens were detected, including Arsenic, Nitrate, Chromium (hexavalent).
Water Provider Information
Contaminants Detected
| Contaminant | Detected Level | EWG Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Perfluorohexane sulfonate (PFHXS) | 0.97 ppt | 0.00 ppt | 10 ppt | Above guideline |
| Arsenic carcinogen | 0.24 ppb | 0.00 ppb | 10 ppb | Above guideline |
| Nitrate carcinogen | 5.16 ppm | 0.14 ppm | 10 ppm | Above guideline |
| Chromium (hexavalent) carcinogen | 0.60 ppb | 0.02 ppb | No legal limit | Above guideline |
| 1,4-Dioxane carcinogen | 0.10 ppb | 0.35 ppb | No legal limit | Below guideline |
| Perfluorooctane sulfonate (PFOS) carcinogen | 0.13 ppt | 0.30 ppt | 4 ppt | Below guideline |
| Vanadium | 1.78 ppb | 21 ppb | No legal limit | Below guideline |
Health Context
Perfluorohexane sulfonate (PFHXS)
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Arsenic carcinogen
Long-term exposure increases risk of skin cancer, bladder cancer, and lung cancer; chronic exposure causes neurological effects and cardiovascular disease.
Nitrate carcinogen
Nitrate is converted to nitrite in the body, which can interfere with oxygen transport in blood. Chronic exposure is linked to increased cancer risk.
Chromium (hexavalent) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
1,4-Dioxane carcinogen
Probable human carcinogen causing liver and kidney damage. Chronic exposure linked to increased cancer risk, particularly liver tumors and nasal cavity cancers.
Recommended Filtration for This Water
Echo RO System
Reverse osmosis filtration removes up to 99.9% of contaminants including heavy metals, PFAS, disinfection byproducts, and more. The gold standard for drinking water purification.
View RO SystemsEcho Whole-Home Filter
Filters water at every tap in your home. Reduces chlorine, VOCs, and disinfection byproducts from your shower, bath, and kitchen water.
View Whole-Home FiltersEcho Hydrogen Water Flask
Once your water is clean, supercharge it. Molecular hydrogen is the smallest, most bioavailable antioxidant — shown to reduce inflammation, boost energy, and support cellular health.
Shop Hydrogen FlaskFrequently Asked Questions
Is Ontario tap water safe to drink?
Ontario tap water meets EPA legal standards for drinking water. However, 4 contaminants exceed stricter EWG health guidelines, and 5 known carcinogens were detected. While legally compliant, additional filtration is recommended for optimal safety.
What contaminants are in Ontario water?
A total of 7 contaminants were detected in Ontario tap water, including Perfluorohexane sulfonate (PFHXS), Arsenic. Of these, 4 exceed EWG health guidelines.
What's the best water filter for Ontario?
For Ontario tap water, we recommend a reverse osmosis (RO) system for drinking water — it removes up to 99.9% of contaminants including heavy metals, PFAS, and disinfection byproducts. For shower and bath water, a whole-home filtration system reduces chlorine and volatile organics.
Where does Ontario get its water?
Ontario tap water is provided by Chino Basin Desalter Authority - Desalter 2, serving approximately 376,341 people. For detailed source water information, contact your local utility or visit the EPA's SDWIS database.
Nearby City Water Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: March 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
