Is Ontario, CA tap water safe?
Data: U.S. EPA · How we read the data · How we check it
Summary
No federal limits exceeded in EPA data for Cucamonga Valley Water District.
5 public water systems serve parts of Ontario. The largest, Cucamonga Valley Water District, serves 213,375 people, and 2 systems here had PFAS above a federal limit. Your water bill names your system.
Largest system
Cucamonga Valley Water District
213,375 people · Surface water · EPA ID CA3610018
Buys treated water from San Gabriel Valley Water Company – Fontana, City of Upland, Ontario Municipal Utilities Company.
| PFAS | Highest average | Limit |
|---|---|---|
| PFOA Not detected | – | 4 ppt |
| PFOS Not detected | – | 4 ppt |
| PFHxS Not detected | – | 10 ppt |
| PFNA Not detected | – | 10 ppt |
| HFPO-DA (GenX) Not detected | – | 10 ppt |
ppt = parts per trillion. "Highest average" is the highest average at any of the system's entry points, the way EPA compares results with the limits.
Lead: 0 ppb at the 90th percentile (Dec 2024, and 9 in 10 homes sampled were at or below it) Below action level
Health-based violations since 2016: 0
Across California, 129 of 691 water systems EPA tested had PFAS above a 2024 federal limit, and 26 systems were above the lead action level in results from the last five years. California results.
Ontario homes and lead pipes
Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. Renting? Ask your landlord what the service line is made of, because it's their pipe to replace. How to check your own line.
Housing: Census American Community Survey 2020–2024 5-year estimates for Ontario city (tables B25034, B25003). Estimates for small places have a margin of error.
Which system serves your ZIP code
Based on the ZIP codes each system reported serving. Boundaries don't follow ZIP lines exactly, so your water bill is the final word.
| System | ZIP codes in Ontario |
|---|---|
| Ontario Municipal Utilities Company 185,010 people | 91761, 91762 |
| Cucamonga Valley Water District 213,375 people | 91764 |
Other water systems serving Ontario
- Ontario Municipal Utilities Company185,010 people · Purchased surface water · California · lists this cityPFOA above limitAlso: PFOS detected · PFHxS detected
- Western Municipal Water District87,955 people · Purchased surface water · California · reported ZIPs herePFHxS detectedAlso: Lithium above screening level
- Monte Vista Water District56,390 people · Purchased surface water · California · reported ZIPs herePFOS above limitAlso: PFHxS detected
- Bryan County Rws & Swmd #26,270 people · Surface water · Oklahoma · reported ZIPs hereTotal trihalomethanes (TTHM) violationsAlso: Haloacetic acids (HAA5) violation
How nearby cities compare
| City | PFAS | Lead (90th pct.) |
|---|---|---|
| Chino 5 mi City of Chino | None above limits | 1 ppb |
| Eastvale 5 mi Elsinore Valley Municipal Water District | None above limits | 1.3 ppb |
| Montclair 6 mi Monte Vista Water District | Above limit | 0 ppb |
| Upland 6 mi Cucamonga Valley Water District | None above limits | 0 ppb |
| Rancho Cucamonga 6 mi Cucamonga Valley Water District | None above limits | 0 ppb |
| Jurupa Valley 8 mi Jurupa Community Services District | None above limits | 0 ppb |
Questions
Is Ontario tap water safe to drink?
Cucamonga Valley Water District has had no health-based violations since 2016. Utility data can't show lead from your own pipes: if your home was built before 1986, test your tap. Your utility's annual Consumer Confidence Report is the official summary.
Who supplies water in Ontario, CA?
5 public water systems serve parts of Ontario. The largest is Cucamonga Valley Water District (213,375 people). Your water bill names your system. The EPA ID is also on your utility's Consumer Confidence Report.
Does Ontario tap water have PFAS?
None detected above EPA's reporting limits. Cucamonga Valley Water District had no PFAS detected in EPA's 2023–2025 testing. "Not detected" means below the reporting limit (about 2 to 20 ppt), not proven zero.
Do Ontario homes have lead pipes?
Census estimates put 50% of Ontario homes as built before 1980 (California: 56%). Lead service lines and lead solder were allowed until 1986, so older homes are more likely to have them. Cucamonga Valley Water District's service line inventory says what your line is made of. The only way to know for your home is to check the line where it enters the house and test your tap.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.