City of Palo Alto water quality
Palo Alto, CA · serves 67,658 people (19,982 connections) · Purchased surface water · Local government · EPA ID CA4310009
Data: U.S. EPA · How we read the data · How we check it
Buys water from San Francisco Regional Water System, Stanford University Water System, City of East Palo Alto, Purissima Hills Water District, City of Mountain View. Treated water bought from another system can carry that system's contaminants.
Summary
No federal limits exceeded in EPA data.
- PFAS
- Not detectedNone of 29 PFAS found above EPA's reporting limits in 4 samples (2023–2025).
- Lead
- Below action level0 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period ending Dec 2023. Your home's pipes can make yours higher.
- Violations
- None health-basedNo health-based violations since 2016.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read City of Palo Alto's annual water quality report (Consumer Confidence Report). It lists every regulated contaminant tested and is usually on the utility's website or mailed with your bill, and you can also request it at (650) 496-5098. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 1 entry point tested Sep 2023 to Jun 2024. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA Not detected Limit 4 ppt | – |
| PFOS Not detected Limit 4 ppt | – |
| PFHxS Not detected Limit 10 ppt | – |
| PFNA Not detected Limit 10 ppt | – |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Not detected Limit 1 | – |
| PFBS Not detected Guideline 2,000 ppt | – |
| PFBA Not detected Guideline 6,000 ppt | – |
| PFHxA Not detected Guideline 3,000 ppt | – |
29 PFAS tested, 0 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Not detected in 4 samples (reporting limit 9 ppb). About lithium.
Lead and copper
Latest 90th percentile: 0 ppb lead (Jan 2021 – Dec 2023). Below action level
Highest since 2016: 1.1 ppb (Dec 2016).
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2021 – Dec 2023 | 0 ppb |
| Jan 2018 – Dec 2020 | 0 ppb |
| Jan 2015 – Dec 2017 | 0 ppb |
Earlier results (9)
| Jan 2014 – Dec 2016 | 1.1 ppb |
| Jan 2011 – Dec 2013 | 1.03 ppb |
| Jan 2008 – Dec 2010 | 3 ppb |
| Jan 2007 – Dec 2007 | 3.7 ppb |
| Jan 2006 – Dec 2006 | 3 ppb |
| Jan 2005 – Dec 2005 | 14.2 ppb |
| Jan 2003 – Dec 2005 | 1 ppb |
| Jan 2004 – Dec 2004 | 12.7 ppb |
| Jan 2003 – Dec 2003 | 1 ppb |
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Earlier EPA testing (2013–2020)
| Contaminant | Highest | Guideline |
|---|---|---|
| Manganese | 5 ppb | 300 ppb |
| Chlorate | 260 ppb | 210 ppb |
| Chromium-6 | 0.21 ppb | – |
| Strontium | 0.24 ppm | 1.5 ppm |
| Vanadium | 0.6 ppb | 21 ppb |
Where it serves
ZIP codes the system reported serving: 94022, 94301, 94302, 94303, 94304, 94306
Nearby utilities
- California Water Service – Bear Gulch Palo Alto · same area
- California Water Service Los Altos Suburban Los Altos · 3 mi
- City of Mountain View Mountain View · 4 mi
- City of Sunnyvale Sunnyvale · 6 mi
- City of Redwood City Redwood City · 9 mi
- City of Santa Clara Santa Clara · 10 mi
Questions
Is City of Palo Alto water safe to drink?
City of Palo Alto has no health-based violations since 2016. EPA testing found no PFAS above the federal limits. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does City of Palo Alto water have PFAS?
EPA tested City of Palo Alto for 29 PFAS between Sep 2023 and Jun 2024 and none were detected above the reporting limits (about 2 to 20 ppt depending on the chemical).
What is the lead level in City of Palo Alto water?
The most recent 90th-percentile lead result for City of Palo Alto is 0 ppb, for the period ending Dec 2023. The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for CA4310009: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID CA4310009).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask City of Palo Alto at (650) 496-5098, or see EPA's guide to finding it.
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.