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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Real EPA measurements of arsenic for California water systems — Six-Year Review compliance samples 2012–2019 (historical). Methodology
These cities have arsenic levels above 50% of the EPA limit but within compliance
Every California system with a arsenic result in EPA's data, sorted by level. Averages of 2012–2019 finished-water samples, non-detects counted as zero — historical, not today's tap.
| City | Level | Period | EPA Limit | % of Limit | Status |
|---|---|---|---|---|---|
| ParamountGrade A | 5.71 ug/LAverage of 564 samples | 2012–2019 | 10.00 ug/L | 57.1% | Warning |
| DavisGrade A | 5.70 ug/LAverage of 1 samples | 2012–2019 | 10.00 ug/L | 57.0% | Warning |
| Chino HillsGrade A | 4.93 ug/LAverage of 179 samples | 2012–2019 | 10.00 ug/L | 49.3% | Safe |
| VictorvilleGrade A | 4.55 ug/LAverage of 1400 samples | 2012–2019 | 10.00 ug/L | 45.5% | Safe |
| SalinasGrade A | 4.40 ug/LAverage of 93 samples | 2012–2019 | 10.00 ug/L | 44.0% | Safe |
| MantecaGrade B | 4.15 ug/LAverage of 4690 samples | 2012–2019 | 10.00 ug/L | 41.5% | Safe |
| LakewoodGrade B | 3.95 ug/LAverage of 312 samples | 2012–2019 | 10.00 ug/L | 39.5% | Safe |
| MercedGrade C | 3.83 ug/LAverage of 111 samples | 2012–2019 | 10.00 ug/L | 38.3% | Safe |
| LancasterGrade A | 3.73 ug/LAverage of 708 samples | 2012–2019 | 10.00 ug/L | 37.3% | Safe |
| Paso RoblesGrade B | 3.38 ug/LAverage of 180 samples | 2012–2019 | 10.00 ug/L | 33.8% | Safe |
| DelanoGrade A | 3.18 ug/LAverage of 1197 samples | 2012–2019 | 10.00 ug/L | 31.8% | Safe |
| Palm DesertGrade A | 2.89 ug/LAverage of 857 samples | 2012–2019 | 10.00 ug/L | 28.9% | Safe |
| BakersfieldGrade C | 2.69 ug/LAverage of 580 samples | 2012–2019 | 10.00 ug/L | 26.9% | Safe |
| EncinitasGrade A | 2.61 ug/LAverage of 8 samples | 2012–2019 | 10.00 ug/L | 26.1% | Safe |
| El MonteGrade A | 2.60 ug/LAverage of 3 samples | 2012–2019 | 10.00 ug/L | 26.0% | Safe |
| Lake ElsinoreGrade A | 2.41 ug/LAverage of 128 samples | 2012–2019 | 10.00 ug/L | 24.1% | Safe |
| AzusaGrade C | 2.14 ug/LAverage of 233 samples | 2012–2019 | 10.00 ug/L | 21.4% | Safe |
| TemeculaGrade C | 2.01 ug/LAverage of 859 samples | 2012–2019 | 10.00 ug/L | 20.1% | Safe |
| Elk GroveGrade A | 1.96 ug/LAverage of 247 samples | 2012–2019 | 10.00 ug/L | 19.6% | Safe |
| Monterey ParkGrade D | 1.82 ug/LAverage of 1397 samples | 2012–2019 | 10.00 ug/L | 18.2% | Safe |
| PerrisGrade A | 1.77 ug/LAverage of 86 samples | 2012–2019 | 10.00 ug/L | 17.7% | Safe |
| PittsburgGrade A | 1.69 ug/LAverage of 15 samples | 2012–2019 | 10.00 ug/L | 16.9% | Safe |
| Los AngelesGrade A | 1.49 ug/LAverage of 569 samples | 2012–2019 | 10.00 ug/L | 14.9% | Safe |
| RiversideGrade B | 1.33 ug/LAverage of 661 samples | 2012–2019 | 10.00 ug/L | 13.3% | Safe |
| IrvineGrade A | 1.24 ug/LAverage of 648 samples | 2012–2019 | 10.00 ug/L | 12.4% | Safe |
Showing 25 of 72 cities. View individual city pages for detailed reports.
Arsenic is a known human carcinogen linked to cancers of the skin, bladder, lung, kidney, and liver. Long-term exposure can cause skin damage including color changes and lesions. Arsenic exposure is associated with cardiovascular disease, diabetes, and neurological effects. Studies have shown links between arsenic exposure and developmental effects in children, including reduced IQ and learning disabilities.
Erosion of natural deposits in the earth; runoff from orchards; discharge from glass and petroleum refineries
Based on our analysis of EPA Safe Drinking Water Information System (SDWIS) data and local water utility reports,arsenic has been detected in 72 California water systems. The average level across all tested cities is 12% of the EPA Maximum Contaminant Level (MCL), with the highest detection at 57.1% of the limit.
The EPA set the arsenic MCL at 0.010 mg/L (10 ppb) in 2001. The EPA MCL for arsenic is 0.01 mg/L. This limit is set to protect public health based on available scientific evidence about the contaminant's health effects.
72 California cities have arsenic detected in their water supply. All tested cities are within EPA safety limits.
Increased cancer risk (skin, bladder, lung), skin damage, cardiovascular disease, diabetes. The most vulnerable groups include children and people with cardiovascular conditions.
The most effective methods for removing arsenic include Reverse Osmosis, Adsorption Media (Iron-Based), Distillation. Look for filters certified by NSF/ANSI for arsenic reduction.
The EPA Maximum Contaminant Level (MCL) for arsenic is 0.01 mg/L.The EPA set the arsenic MCL at 0.010 mg/L (10 ppb) in 2001.
This page shows what California utilities reported for arsenic. It cannot tell you what is coming out of your own tap: utility samples are taken across a whole system and averaged, levels vary by address and season, and anything picked up after the water leaves the main never appears in their report.
Home water test kitscheck your own tap before buying any filterRecommended filtration methods for arsenic removal:
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Paid links. We earn a commission if you buy, at no extra cost to you. Filters are matched to the removal methods listed above for arsenic.