Ontario Water Quality
California
According to EPA SDWIS, Ontario, California is served by 3 community water systems covering about 185,010 people. PlainEnviro's health-based extract shows zero health-based violation records for those systems. Counts are historical EPA registry rows, not a current compliance or drinkability score.
Drinking water in Ontario, California is delivered through 3 EPA-regulated community water systems serving an estimated 185,010 people. Each system is tracked in the EPA Safe Drinking Water Information System (SDWIS) under the Safe Drinking Water Act, which requires testing for regulated contaminants, consumer notification of violations, and publication of an annual Consumer Confidence Report.
PlainEnviro's health-based SDWIS extract shows 0 violation records across the 3 active community systems shown here. Monitoring and reporting records are not present in the extract. No contaminant code appears in the health-based records. 23 TRI-reporting industrial facilities are also located within the city limits.
A past EPA health-based registry row does not describe water delivered today or current compliance status; utilities notify customers and remediate under state primacy oversight when required. For current water-quality status and treatment practices, review your local utility's most recent Consumer Confidence Report or contact the California drinking water program. All records above reflect federal EPA SDWIS data and are not independently verified against state databases.
Community Water Systems
| System Name | Pop. Served | Violations | Status |
|---|---|---|---|
| ONTARIO MUNICIPAL UTILITIES COMPANY | 185,010 | 0 | Clean |
| CHINO BASIN DESALTER AUTH. - DESALTER 2 | 0 | 0 | Clean |
| CHINO BASIN DESALTER AUTH. - DESALTER 1 | 0 | 0 | Clean |
TRI Facilities in Ontario
| Facility | Total Releases |
|---|---|
| New-Indy Containerboard Ontario LLC | 542.4K lbs |
| Armorcast Products Co | 33.7K lbs |
| Hudson Technologies Co | 17.1K lbs |
| Linde Inc | 14.2K lbs |
| Alltech Inc | 13.1K lbs |
| Sherwin-Williams Co | 5.5K lbs |
| Elite Comfort Solutions | 4.5K lbs |
| Prc Composites LLC | 2.5K lbs |
| Sterigenics-Ontario Facility | 473 lbs |
| L&p Financial Services Co. | 33 lbs |
Frequently Asked Questions
What does EPA SDWIS list for drinking water in Ontario, California? ▼
How many water violations does Ontario have in this EPA extract? ▼
How many water systems serve Ontario? ▼
Where does Ontario get its drinking water? ▼
Are there pollution sources near Ontario? ▼
How does Ontario compare in California?
Of the 912 California places with at least one community water system on file, Ontario ranks #275 by number of systems (3).
Either side of it: Oak View (3), Ocotillo (3), Pala (3), Petaluma (3)
About This Data
Figures here are the current EPA SDWIS extract joined to the 3 community water systems whose service area lists Ontario, ranked against the 912 California places with at least one system on file. Data current as of 2026-08-25.
Water system data comes from the EPA's Safe Drinking Water Information System (SDWIS). PlainEnviro's violation fetch is restricted upstream to records EPA flags as health-based and then joined to active community water systems. Monitoring and reporting violations are not included.
A health-based violation row in this extract is a historical EPA registry entry. It does not describe water delivered today or current compliance status. Many records are later resolved, and public water systems notify customers when required. For current conditions, contact your local water utility or the state drinking water program.
TRI facility data comes from the EPA Toxic Release Inventory. Facilities shown are those that self-report to the TRI program. PlainEnviro presents this data without advocacy framing.
Read our methodology - how this data is sourced, computed, and verified.