Tap Water Quality Report
Tap water quality in PALO ALTO, California
Tap water in PALO ALTO, California receives a grade of D (67/100) from TapWaterSafety.org. It's served by CITY OF PALO ALTO. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in PALO ALTO's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving PALO ALTO.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 31.7 ppb, 529x above the EWG health guideline of 0.06 ppb.
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.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 33.2 ppb, 221x above the EWG health guideline of 0.15 ppb.
Recommended filters for PALO ALTO
Filters matched to the specific contaminants in PALO ALTO's 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.
All contaminants detected in PALO ALTO'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 (HAA9) Disinfection byproduct |
31.7 ppb | 0.06 | — | — | — | — | — | 529× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
33.2 ppb | 0.15 | 80.0 | 100 | — | — | — | 221× over |
| Trichloroacetic acid Disinfection byproduct |
12.4 ppb | 0.1 | — | — | — | — | — | 124× over |
| Dichloroacetic acid Disinfection byproduct |
16.9 ppb | 0.2 | — | — | — | — | — | 85× over |
| Chloroform Disinfection byproduct |
31.7 ppb | 0.4 | — | — | — | — | — | 79× over |
| Bromodichloromethane Disinfection byproduct |
1.15 ppb | 0.06 | — | — | — | — | — | 19× over |
| Chromium (hexavalent) Heavy metal |
0.0825 ppb | 0.02 | — | — | — | — | — | 4.1× over |
| Dibromoacetic acid Disinfection byproduct |
0.0747 ppb | 0.03 | — | — | — | — | — | 2.5× over |
| Dibromochloromethane Disinfection byproduct |
0.0646 ppb | 0.1 | — | — | — | — | — | Below guideline |
| Chlorate Disinfection byproduct |
127.9 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
12.9 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Vanadium Other |
0.238 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.179 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.0715 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Quinoline Other |
0.0055 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 PALO ALTO.