Ontario, CA water quality
Ontario, CA is served by 3 public water systems, serving 185,210 people combined. Across those systems, we count 0 health-based violations in the last 5 years. The worst Tap Grade among them is B.
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Is Ontario, CA tap water safe to drink?
3 public water systems serve Ontario, CA, with 0 health-based violations in the last 5 years across them. The worst Tap Grade among them is B.
Does Ontario's water have lead in it?
The most recent 90th-percentile lead sample is 0.6 ppb, versus the EPA action level of 15 ppb.
Has PFAS been detected in Ontario's water?
Yes — at least one water system serving Ontario has detected PFAS under UCMR5.
Other cities in California
See all of California →Source: EPA SDWIS/ECHO · Data as of 2026Q2