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Ontario, CA Tap Water Quality 2026

Water quality report for Ontario, CA — PFAS, lead and copper results, violation history and state inspection findings from EPA SDWIS.

A look at Ontario's drinking water using EPA enforcement records: violations, lead and copper results, PFAS sampling and state inspection findings.

Main Utility: Ontario Municipal Utilities Company PWSID: CA3610034 Updated: 2026 Q2
⚠️

PFAS above the federal limit at 1 of 17 sampling points

Lead is 0.60 ppb, 4% of the action level and no violations are open. However, PFAS exceeds the federal limit at 1 of 17 sampling points, running as high as 3.75 times the limit.

C

Ontario earns a C for water quality

Graded on violations, lead, and PFAS, with state inspection findings.

Lead: 0.60 ppb — 4% of the federal action level
PFAS above the federal limit at 1 of 17 sampling points
No violations since 2015
No violations currently open
Ontario's lead level vs. all California community water systems
0 ppb5 ppb10 ppb15 ppb
Lead level: 0.60 ppb — 4% of the federal action level
✓ Lower lead than 98% of California utilities
Population Served
164545
~39996 connections
Water Source
Surface water
Purchased from another system — SDWIS source code SWP
Active Violations
0
None on record since 2015

Lead & Copper Testing

Lead (Pb)
90th percentile of tap samples collected across the distribution system
4% of EPA action level
0.60 ppb
Action level: 15 ppb
The 90th-percentile lead result is 0.60 ppb, 4% of the 15 ppb federal action level. The action level is a treatment trigger, not a legal maximum, and it is measured across sampled taps rather than at any single home.

Contaminant Violations (2015–Present)

✓ No violations on record for this water system.
Understanding violation types MCL violations mean a contaminant exceeded the federal maximum limit — the most serious type.
TT (Treatment Technique) violations mean required treatment procedures weren't followed, but don't necessarily mean contamination occurred.

Violation History

No violations are on record for this system since 2015. EPA records violations for every community water system, so this reflects a clean compliance history rather than missing data.

About the Main Water System

Utility Ontario Municipal Utilities Company
PWSID CA3610034
Water source Surface water — Purchased from another system — SDWIS source code SWP
Population served 164,545
Service connections 39,996
Systems serving this area 6
Regulator State primacy agency
Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Ontario tap water safe to drink? ▼
It meets most federal standards, but PFAS exceeds the federal limit at 1 of 17 sampling points. No violations are currently open. Lead is 0.60 ppb, 4% of the action level.
Does Ontario water have PFAS? ▼
Yes. PFAS exceeds the federal limit at 1 of 17 sampling points, running as high as 3.75 times the limit. Limits are enforced on a running annual average at each sampling point, not on a single sample.
Who supplies water to Ontario? ▼
Ontario Municipal Utilities Company (PWSID CA3610034), one of 6 systems serving this area. Surface water. Purchased from another system — SDWIS source code SWP
When was this system last inspected? ▼
It was last inspected on 2025-07-02. No significant deficiencies were recorded.

What Should Ontario Residents Do?

1
Consider a reverse-osmosis filter
Reverse osmosis removes more than 95% of PFAS. Standard carbon pitchers do not.
2
Check for a lead service line
Lead reaches tap water mainly through service lines and household plumbing. Suppliers now publish an inventory identifying lead lines.
3
Flush before drinking
If water has sat in pipes more than six hours, run the cold tap for two minutes before drinking or cooking.

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