What contaminants are in PALO ALTO tap water?

Public data sources identify the following contaminants in PALO ALTO's water supply: Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Trichloroacetic acid, Dichloroacetic acid, Chloroform, Bromodichloromethane, Chromium (hexavalent), Dibromoacetic acid, Dibromochloromethane, Chlorate, Manganese, Vanadium, Monochloroacetic acid, Strontium, Quinoline. Levels and comparison to EWG health guidelines are listed on the full city page.

Which water utility serves PALO ALTO?

PALO ALTO is served by CITY OF PALO ALTO. CITY OF PALO ALTO serves approximately 67,231 residents.

Tap Water Quality Report

Tap water quality in PALO ALTO, California

Q: Is the tap water in PALO ALTO, California safe to drink?

PALO ALTO's tap water receives a grade of B (80/100) from TapWaterSafety.org. 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. Grades are based on EPA SDWIS, EPA ECHO, EWG Tap Water Database, and the utility's published Consumer Confidence Report.

Served by CITY OF PALO ALTO. 67,231 residents.

Average score 80/100

Utilities 1

Population 67,231

80/100

Good

ⓘ How did we get this rating?

Quick answer

Tap water in PALO ALTO, California receives a grade of B (80/100) 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.

Data sources for this grade: utilities.csv EWG Tap Water Database ⓘ How did we get this rating?

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 concern

Haloacetic 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 concern

Haloacetic 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 concern

Total trihalomethanes (TTHMs) detected at 33.2 ppb, 221x above the EWG health guideline of 0.15 ppb.

EPA compliance record

Official U.S. EPA records for CITY OF PALO ALTO (system ID CA4310009) for the last 3 years. Checked 2026-10-07.

No EPA violations in the last 3 years.

0 of 12quarters with a violation

Nolead above EPA action level

02/26/2025last state inspection

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 PALO ALTO

Filters matched to the specific contaminants in PALO ALTO's water supply.

Carbon filter certified for VOCs (NSF/ANSI 53)

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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.