Water Quality Report · Updated May 12, 2026
WESTERN MWD
WESTERN MWD delivers tap water graded C (67/100) by TapWaterSafety.org. The utility serves approximately 86,062 residents in RIVERSIDE, California using surface water (purchased). 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. For questions, the utility can be reached at 951-789-5119.
Is RIVERSIDE tap water safe to drink?
WESTERN MWD delivers tap water that earns a grade of C (67/100) from TapWaterSafety.org — an average rating, with several contaminants above health guidelines but generally compliant with US legal limits.
The utility serves 86,062 residents in RIVERSIDE, drawing from surface water (purchased).
Public testing data identifies 12 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA5), Perfluorohexane sulfonate (PFHXS), Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Bromodichloromethane, Dibromochloromethane, Dibromoacetic acid, Chromium (hexavalent), Bromoform, Chloroform, Dichloroacetic acid, Trichloroacetic acid. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Quick actions for RIVERSIDE residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for WESTERN MWD.
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.
Contact WESTERN MWD
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for RIVERSIDE
Filters matched to the specific contaminants in this water supply.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 67/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). 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 |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Perfluorohexane sulfonate (PFHXS) PFAS |
0.283 ppt | 0.001 | 10.0 | — | — | — | — | 283× 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 |
| 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 |
| Chromium (hexavalent) Heavy metal |
0.742 ppb | 0.02 | — | — | — | — | — | 37× over |
| Bromoform Disinfection byproduct |
6.84 ppb | 0.5 | — | — | — | — | — | 14× 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 |
| Chlorate Disinfection byproduct |
52.9 ppb | 210.0 | — | — | — | — | — | Below guideline |
| 1,4-Dioxane Semi-volatile organic compound |
0.0763 ppb | 0.35 | — | — | 50 | 1 | — | Below guideline |
| Vanadium Other |
4.15 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
2.77 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
1.7 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.208 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.0292 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Perfluoropentanoic Acid (PFPeA) PFAS |
0.783 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.297 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Perfluorobutane sulfonate (PFBS) PFAS |
0.25 ppt | 2000.0 | — | — | — | — | — | Below guideline |
| Germanium Other |
0.131 ppb | — | — | — | — | — | — | Below guideline |
| Lithium Other |
1.33 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 (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
WESTERN MWD service area
This water system serves 1 community in Riverside County, California. Click any city for its dedicated tap water quality page.
Find the right filter for RIVERSIDE water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.