City of Palo Alto serves 67,658 people from surface water. 31 results are on record. No measured result is above a legal limit.
No measured result is above a legal limit.
20,872service lines inventoried
From the utility's inventory reported to EPA (2026Q2). Look up your address with the utility.
0health-based violations in the last 10 years
From EPA SDWIS. A clean violation history means no enforcement action was recorded; it does not cover contaminants without a limit.
No result is not a pass. Your utility's annual water quality report may list them, and a certified lab test covers your own tap.
A federal limit (an MCL or action level) is an enforceable legal cap; a health goal is often stricter. Meeting the limit is a compliance fact, not a health clearance, and PurityMap publishes no overall compliance verdict.
The records describe the system. A certified lab test shows what reaches your glass.
Screening tells you if something is worth a closer look; a lab result is the number you can act on.
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Screening: quick check, not lab-grade
Silver Lake Research
Lead, bacteria, nitrate, copper, iron, chlorine, hardness and pH
What it can't tell you: Each test gives a yes/no or a rough range, not a lab number, and it cannot detect PFAS or arsenic.
Lab-certified results
ETR Laboratories
50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria
CITY OF PALO ALTO (PWS ID CA4310009) is a public water system serving 67,658 people in Palo Alto, California.
CITY OF PALO ALTO is on record as drawing from surface water. The source shapes which contaminants matter most for this system.
PurityMap's record for CITY OF PALO ALTO holds 31 findings: 31 not detected, from 31 evidence records. Every finding links to its source; a substance that was never monitored is shown as pending, not as a pass.
PurityMap does not issue a safety verdict. It publishes CITY OF PALO ALTO's measured results against each contaminant's benchmark so you can read them in context. Safety depends on the specific finding, your plumbing, and how the water reaches your tap.
The latest published record for CITY OF PALO ALTO is dated 2026-10-15. Utilities report on regulatory cycles, so results reflect the monitoring period rather than a live reading.
No. It is assessed at the water-system level from CITY OF PALO ALTO's own monitoring. It does not cover the service line to your building or the plumbing inside it, which can add lead and other metals after the water leaves the system. A tap test is the way to know what reaches your glass.
Follow City of Palo Alto
One email when a new sampling round is published, a result moves above or below its reference, or the system's score changes.
Follow this water →As listed for this system in EPA's records. Your water bill names your supplier.
| Substance | Result | Reference | Sampled | Status | Evidence |
|---|---|---|---|---|---|
| 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) | < 5 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS) | < 2 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | 2023-10-05 to 2024-06-18 | Not detected | — |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | 2023-09-06 to 2024-06-18 | Not detected | — |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | 2023-09-06 to 2024-06-18 | Not detected | — |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorobutanesulfonic acid (PFBS) | < 3 ng/L | 2,000 ng/L EPA health advisory (screening, not a legal limit) | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | 2023-10-05 to 2024-06-18 | Not detected | View evidence |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | 2023-10-05 to 2024-06-18 | Not detected | View evidence |
| Perfluorooctanesulfonic acid (PFOS) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | 2023-10-05 to 2024-06-18 | Not detected | View evidence |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | 2023-09-06 to 2024-06-18 | Not detected | — |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | 2023-09-06 to 2024-06-18 | Not detected | — |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | 2023-10-05 to 2024-06-18 | Not detected | — |
| Lithium | < 9 µg/L | 10 µg/L EPA health reference level (screening, not a legal limit) | 2023-09-06 to 2024-06-18 | Not detected | — |
| Lead (90th percentile) | Non-Detect (ND) | 15 µg/L federal action level | 2021–2023 monitoring period | Not detected | View evidence |
UCMR5 Analytical Results
UCMR5 Analytical Results: CITY OF PALO ALTO (CA4310009)
US EPA
State SDWIS Compliance Record
Lead & Copper Rule 90th-percentile: CITY OF PALO ALTO (CA4310009)
US EPA SDWIS
What it can't tell you: It does not test PFAS, and not every result on the panel falls under the lab's accredited scope.
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