Tap Water Quality Report
Tap water quality in Riverside, California
Tap water in Riverside, California receives a grade of D (66/100) from TapWaterSafety.org. It's served by 2 public water systems, primarily WESTERN MWD. The most significant water quality concerns are: Haloacetic acids (HAA5) significantly above health guideline; Perfluorohexane sulfonate (PFHXS) significantly above health guideline; Haloacetic acids (HAA9) significantly above health guideline; PFAS contamination; Arsenic significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in Riverside's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utilities serving Riverside.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 36.2 ppb, 362x above the EWG health guideline of 0.1 ppb.
Perfluorohexane sulfonate (PFHXS) significantly above health guideline
Moderate concernPerfluorohexane sulfonate (PFHXS) detected at 0.283 ppt, 283x above the EWG health guideline of 0.001 ppt.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 9.68 ppb, 161x above the EWG health guideline of 0.06 ppb.
PFAS contamination
Severe concernPerfluorooctane sulfonate (PFOS), Perfluorooctanoic acid (PFOA) detected. PFAS are persistent chemicals linked to cancer and immune effects with no known safe exposure threshold.
Arsenic significantly above health guideline
Moderate concernArsenic detected at 2.1 ppb, 526x above the EWG health guideline of 0.004 ppb.
EPA compliance record
Official U.S. EPA records for WESTERN MWD (system ID CA3310049) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Water systems serving Riverside
Riverside is served by 2 public water systems. Click any utility to see its complete grade card and treatment plant contact info.
WESTERN MWD
- Haloacetic acids (HAA5) significantly above health guideline
- Perfluorohexane sulfonate (PFHXS) significantly above health guideline
- Haloacetic acids (HAA9) significantly above health guideline
RIVERSIDE, CITY OF
- PFAS contamination
- Perfluorohexane sulfonate (PFHXS) significantly above health guideline
- Arsenic significantly above health guideline
Recommended filters for Riverside
Filters matched to the specific contaminants in Riverside's water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in Riverside's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Perfluorohexane sulfonate (PFHXS) PFAS |
2.24 ppt | 0.001 | 10.0 | — | — | — | — | 2238× over |
| Arsenic Heavy metal |
2.1 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 526× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
9.68 ppb | 0.06 | — | — | — | — | — | 161× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
24.2 ppb | 0.15 | 80.0 | 100 | — | — | — | 161× over |
| Chromium (hexavalent) Heavy metal |
2.07 ppb | 0.02 | — | — | — | — | — | 104× over |
| Bromodichloromethane Disinfection byproduct |
5.52 ppb | 0.06 | — | — | — | — | — | 92× over |
| Dibromochloromethane Disinfection byproduct |
7.73 ppb | 0.1 | — | — | — | — | — | 77× over |
| Dibromoacetic acid Disinfection byproduct |
1.41 ppb | 0.03 | — | — | — | — | — | 47× over |
| Nitrate Inorganic |
5.54 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 40× over |
| Perfluorooctanoic acid (PFOA) PFAS |
3.11 ppt | 0.09 | 4.0 | 100 | 100 | 0.007 | — | 35× over |
| Uranium Radiological |
6.72 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 16× over |
| Bromoform Disinfection byproduct |
6.84 ppb | 0.5 | — | — | — | — | — | 14× over |
| Perfluorooctane sulfonate (PFOS) PFAS |
3.8 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | 13× over |
| Chloroform Disinfection byproduct |
3.96 ppb | 0.4 | — | — | — | — | — | 9.9× over |
| Dichloroacetic acid Disinfection byproduct |
1.07 ppb | 0.2 | — | — | — | — | — | 5.4× over |
| Trichloroacetic acid Disinfection byproduct |
0.478 ppb | 0.1 | — | — | — | — | — | 4.8× over |
| Radium, combined (-226 and -228) Radiological |
0.11 pCi/L | 0.05 | 5.0 | — | — | — | — | 2.3× over |
| 1,4-Dioxane Semi-volatile organic compound |
0.65 ppb | 0.35 | — | — | 50 | 1 | — | 1.9× over |
| Perchlorate Disinfection byproduct |
1.27 ppb | 1.0 | — | — | — | — | — | 1.3× over |
| Vanadium Other |
6.38 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Chlorate Disinfection byproduct |
62.3 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
4.23 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
1.7 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Chloromethane Other |
0.0273 ppb | 2.69 | — | — | — | — | — | Below guideline |
| Perfluoropentanoic Acid (PFPeA) PFAS |
4.84 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorohexanoic Acid (PFHxA) PFAS |
3.95 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.208 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Perfluorobutanoic Acid (PFBA) PFAS |
3.08 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.0292 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Perfluorobutane sulfonate (PFBS) PFAS |
1.93 ppt | 2000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.493 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Perfluoroheptanoic acid (PFHPA) PFAS |
0.249 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.481 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Germanium Other |
0.278 ppb | — | — | — | — | — | — | Below guideline |
| Lithium Other |
4.53 ppb | — | — | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from WESTERN MWD.