Tap Water Quality Report
Tap water quality in RANCHO CUCAMONGA, California
Tap water in RANCHO CUCAMONGA, California receives a grade of D (66/100) from TapWaterSafety.org. It's served by CUCAMONGA VALLEY WATER DISTRICT. The most significant water quality concerns are: Haloacetic acids (HAA5) significantly above health guideline; Haloacetic acids (HAA9) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; Arsenic detected. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in RANCHO CUCAMONGA's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving RANCHO CUCAMONGA.
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.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 17.8 ppb, 297x above the EWG health guideline of 0.06 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 21.9 ppb, 146x above the EWG health guideline of 0.15 ppb.
Arsenic detected
Moderate concernArsenic detected at 0.414 ppb.
EPA compliance record
Official U.S. EPA records for CUCAMONGA VALLEY WATER DISTRICT (system ID CA3610018) 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.
Recommended filters for RANCHO CUCAMONGA
Filters matched to the specific contaminants in RANCHO CUCAMONGA'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.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
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 RANCHO CUCAMONGA'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 |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
17.8 ppb | 0.06 | — | — | — | — | — | 297× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
21.9 ppb | 0.15 | 80.0 | 100 | — | — | — | 146× over |
| Arsenic Heavy metal |
0.414 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 103× over |
| Dibromoacetic acid Disinfection byproduct |
2.26 ppb | 0.03 | — | — | — | — | — | 75× over |
| Bromodichloromethane Disinfection byproduct |
3.78 ppb | 0.06 | — | — | — | — | — | 63× over |
| Chromium (hexavalent) Heavy metal |
1.26 ppb | 0.02 | — | — | — | — | — | 63× over |
| Dibromochloromethane Disinfection byproduct |
5.83 ppb | 0.1 | — | — | — | — | — | 58× over |
| Nitrate Inorganic |
3.13 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 22× over |
| Trichloroacetic acid Disinfection byproduct |
1.72 ppb | 0.1 | — | — | — | — | — | 17× over |
| Bromoform Disinfection byproduct |
7.08 ppb | 0.5 | — | — | — | — | — | 14× over |
| Chloroform Disinfection byproduct |
5.2 ppb | 0.4 | — | — | — | — | — | 13× over |
| Nitrate and nitrite Inorganic |
1.3 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 9.3× over |
| Dichloroacetic acid Disinfection byproduct |
1.81 ppb | 0.2 | — | — | — | — | — | 9.1× over |
| 1,2-Dibromo-3-chloropropane (DBCP) Other |
0.0153 ppb | 0.0017 | 0.2 | — | — | — | — | 9.0× over |
| Uranium Radiological |
1.41 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 3.3× over |
| Vanadium Other |
7.52 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Chlorate Disinfection byproduct |
62.6 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Perchlorate Disinfection byproduct |
0.138 ppb | 1.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
3.27 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
43.2 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Trichloroethylene Volatile organic compound |
0.0118 ppb | 0.4 | 5.0 | 10 | 20 | 1.7 | — | Below guideline |
| Aluminum Heavy metal |
10.3 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Manganese Heavy metal |
1.44 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Selenium Heavy metal |
0.336 ppb | 30.0 | 50.0 | 20 | 40 | 30 | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.142 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.249 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.194 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Quinoline Other |
0.00165 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 CUCAMONGA VALLEY WATER DISTRICT.