Water Quality Report · Updated May 12, 2026
CITY OF GILROY
CITY OF GILROY delivers tap water graded F (54/100) by TapWaterSafety.org. The utility serves approximately 59,203 residents in GILROY, California using groundwater. 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. For questions, the utility can be reached at 408-846-0223.
Is GILROY tap water safe to drink?
CITY OF GILROY delivers tap water that earns a grade of F (54/100) from TapWaterSafety.org — a poor rating, with significant contamination concerns and/or recent violations.
The utility serves 59,203 residents in GILROY, drawing from groundwater.
Public testing data identifies 14 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA5), Perfluorohexane sulfonate (PFHXS), Nitrate, Chromium (hexavalent), Nitrate and nitrite, Dibromoacetic acid, Total trihalomethanes (TTHMs), Dibromochloromethane, Haloacetic acids (HAA9), Bromodichloromethane, Perfluorooctanoic acid (PFOA), Bromoform, Tetrachloroethylene (perchloroethylene), Perfluorooctane sulfonate (PFOS). 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 GILROY residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for CITY OF 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.
Contact CITY OF GILROY
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 GILROY
Filters matched to the specific contaminants in this water supply.
Reverse Osmosis or NSF P473 certified carbon
$80-$750Activated carbon and RO are the only technologies proven to remove PFAS at certified levels.
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 54/100 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 |
0.196 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 (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
CITY OF GILROY service area
This water system serves 1 community in Santa Clara County, California. Click any city for its dedicated tap water quality page.
Find the right filter for GILROY water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.