Tap Water Quality Report
Tap water quality in GILROY, California
Tap water in GILROY, California receives a grade of D (66/100) from TapWaterSafety.org. It's served by CITY OF GILROY. The most significant water quality concerns are: PFAS contamination; Haloacetic acids (HAA5) significantly above health guideline; Perfluorohexane sulfonate (PFHXS) significantly above health guideline; Nitrate significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in GILROY's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving GILROY.
PFAS contamination
Severe concernPerfluorooctanoic acid (PFOA), Perfluorooctane sulfonate (PFOS) detected. PFAS are persistent chemicals linked to cancer and immune effects with no known safe exposure threshold.
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 0.196 ppt, 196x above the EWG health guideline of 0.001 ppt.
Nitrate significantly above health guideline
Moderate concernNitrate detected at 5.55 ppm, 40x above the EWG health guideline of 0.14 ppm.
EPA compliance record
Official U.S. EPA records for CITY OF GILROY (system ID CA4310004) 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 GILROY
Filters matched to the specific contaminants in GILROY's water supply.
Filter certified for PFOA/PFOS (NSF/ANSI 53 or 58)
$180-$750Reverse osmosis and some carbon block filters reduce PFAS. Look for certification to NSF/ANSI 53 or 58 for PFOA/PFOS.
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 GILROY'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 |
| Perfluorohexane sulfonate (PFHXS) PFAS |
0.196 ppt | 0.001 | 10.0 | — | — | — | — | 196× over |
| Nitrate Inorganic |
5.55 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 40× over |
| Chromium (hexavalent) Heavy metal |
0.771 ppb | 0.02 | — | — | — | — | — | 39× over |
| Nitrate and nitrite Inorganic |
5.19 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 37× over |
| Dibromoacetic acid Disinfection byproduct |
1.06 ppb | 0.03 | — | — | — | — | — | 35× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
5.07 ppb | 0.15 | 80.0 | 100 | — | — | — | 34× over |
| Dibromochloromethane Disinfection byproduct |
1.82 ppb | 0.1 | — | — | — | — | — | 18× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
0.912 ppb | 0.06 | — | — | — | — | — | 15× over |
| Bromodichloromethane Disinfection byproduct |
0.464 ppb | 0.06 | — | — | — | — | — | 7.7× over |
| Perfluorooctanoic acid (PFOA) PFAS |
0.592 ppt | 0.09 | 4.0 | 100 | 100 | 0.007 | — | 6.6× over |
| Bromoform Disinfection byproduct |
3.08 ppb | 0.5 | — | — | — | — | — | 6.2× over |
| Tetrachloroethylene (perchloroethylene) Volatile organic compound |
0.262 ppb | 0.06 | 5.0 | — | — | — | — | 4.4× over |
| Perfluorooctane sulfonate (PFOS) PFAS |
0.388 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | 1.3× over |
| Vanadium Other |
3.32 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Chlorate Disinfection byproduct |
26.8 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
4.9 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Molybdenum Other |
0.411 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Perfluoropentanoic Acid (PFPeA) PFAS |
1.66 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorohexanoic Acid (PFHxA) PFAS |
1.44 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorobutanoic Acid (PFBA) PFAS |
1.12 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.365 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Perfluorobutane sulfonate (PFBS) PFAS |
0.463 ppt | 2000.0 | — | — | — | — | — | Below guideline |
| Perfluoroheptanoic acid (PFHPA) PFAS |
0.1 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Chlorodifluoromethane Other |
0.0206 ppb | — | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.0856 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| o-toluidine Other |
0.00394 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 CITY OF GILROY.