Excellent Water Quality
| Contaminant | Detected Level | EPA MCL | Health Guideline | Status |
|---|---|---|---|---|
| Lead |
3.1
|
15 ppb | 1 ppb | Warning |
| Compound | Level | EPA MCL | Health Guideline | Status |
|---|---|---|---|---|
| PFOA | 30.0 ppt | 4 ppt | 4 ppt | Exceeded |
| PFHxA | 7.1 ppt | No standard | 400 ppt | Unregulated |
| PFPeA | 6.7 ppt | No standard | — | Unregulated |
| PFBA | 6.4 ppt | No standard | 500 ppt | Unregulated |
| PFOS | 5.2 ppt | 4 ppt | 4 ppt | Exceeded |
| PFPeA | 4.7 ppt | No standard | — | Unregulated |
| PFHxS | 4.2 ppt | 10 ppt | 10 ppt | Below limit |
| PFHxS | 3.4 ppt | 10 ppt | 10 ppt | Below limit |
Water Quality Summary
Tap water quality in Ontario, California (91761) receives an overall grade of A (Excellent) with a score of 85 out of 100, based on analysis of EPA compliance data, contaminant testing, and violation history. This is roughly in line with the California state average of 81. The area is served by 4 water systems providing water to approximately 271,072 people, using surface water and groundwater sources. Testing has found elevated levels of Lead that warrant attention. Notably, 2 PFAS compounds exceed EPA limits — a significant concern given the persistent nature of these chemicals. The area has a clean violation record over the past 5 years — a positive indicator of consistent water quality management.
A score of 85/100 means the water supply in Ontario, CA meets or exceeds all EPA standards with minimal issues. Contaminant levels are well within safe limits, and the water system has maintained a strong compliance record. While no water supply is guaranteed perfect at the tap due to household plumbing, this is among the best-scoring areas in the country.
Health Information
Lead is a toxic metal that can leach from aging pipes and plumbing fixtures.
Even low levels of lead exposure can cause developmental delays in children, kidney damage, and cardiovascular effects in adults. The EPA action level is 15 ppb, but health experts recommend no safe level of lead in drinking water.
Lead enters water primarily through corrosion of lead service lines, lead solder, and brass fixtures — especially in homes built before 1986.
If lead is detected above 1 ppb, consider using a certified lead-removal filter (NSF/ANSI 53) for drinking and cooking water. Run cold water for 30 seconds before use if water has been sitting in pipes.
Common Questions
Based on EPA data, tap water in Ontario, California receives a grade of A (Excellent) with a score of 85/100. This indicates the water meets federal standards and has relatively few concerns. However, individual homes may still have localized issues such as lead from old plumbing.
ZIP code 91761 is served by 4 water systems using surface water, groundwater sources, providing water to approximately 271,072 people. Multiple source types mean your water may come from a blend of surface and underground sources.
Lead was detected at 3.1 ppb in Ontario, California. While this is below the EPA action level of 15 ppb, it exceeds the health guideline of 1 ppb recommended by health organizations. Consider a certified lead filter, especially if you have young children.
Yes — 9 PFAS compounds were detected in water serving Ontario, California, and 2 exceed EPA maximum contaminant levels. PFAS are persistent chemicals linked to cancer, immune system effects, and developmental issues. A reverse osmosis or activated carbon filter certified for PFAS removal is recommended.
Water systems serving Ontario, California have zero violations in the last 5 years. This is a positive indicator of consistent regulatory compliance and water quality management.
Based on detected contaminants (lead, PFAS), residents in Ontario, California should consider: Reverse osmosis (RO) system — most effective for PFAS, lead, and other contaminants. Always look for filters with NSF/ANSI certification for the specific contaminants you want to remove.