Home hazard report for 94023 — Los Altos, CA
ZIP 94023 is served by CWSC Los Altos Suburban: no health-based violations since 2016, latest lead result 1.5 ppb, PFAS 1 detected. Santa Clara is in EPA radon zone 2.
No health-based violations reported since 2016.
90th-percentile lead in the latest round (Jan 2023). Lead comes mostly from household plumbing and service lines, so individual homes can be higher.
PFAS were detected, with PFOA and PFOS below 4.0 ppt (highest not detected).
Predicted average indoor radon between 2 and 4 pCi/L. Test your home; many homes here exceed 4 pCi/L.
Active or proposed Superfund (National Priorities List) sites near the center of this ZIP code.
Active weather alerts
live from the National Weather ServiceChecking the National Weather Service…
Where ZIP 94023 is
blue: utility service area · scroll or pinch to zoomDrinking water: CWSC Los Altos Suburban
Health-based violations
No health-based violations reported since 2016.
Full record for CWSC Los Altos Suburban →
Other systems overlapping this ZIP: Santa Clara Valley Water District.
Lead
90th-percentile lead per sampling round (90% of the homes sampled were at or below this level). Black line: EPA’s 15 ppb action level; under the Lead and Copper Rule Improvements the action level becomes 10 ppb from 2027.
PFAS (“forever chemicals”)
| Compound | Highest result | Samples with detection | EPA limit |
|---|---|---|---|
| PFHxS | 3.5 ppt | 2 of 36 | — |
| PFPeA | not detected | 0 of 36 | — |
| PFBA | not detected | 0 of 36 | — |
| HFPO-DA (GenX) | not detected | 0 of 36 | — |
| PFBS | not detected | 0 of 36 | — |
| PFHpA | not detected | 0 of 36 | — |
| PFNA | not detected | 0 of 36 | — |
| PFOS | not detected | 0 of 36 | 4 ppt MCL |
| PFOA | not detected | 0 of 36 | 4 ppt MCL |
| PFDA | not detected | 0 of 36 | — |
| PFHxA | not detected | 0 of 36 | — |
EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), samples 2023–2025; ppt = parts per trillion (ng/L). The 4.0 ppt maximum contaminant levels for PFOA and PFOS were set by EPA in 2024; water systems have until the end of the decade to comply.
Radon in Santa Clara
EPA radon zone 2 — moderate potential. Predicted average indoor radon between 2 and 4 pCi/L. Test your home; many homes here exceed 4 pCi/L.
Radon is a colorless, odorless radioactive gas from soil and rock, and the leading cause of lung cancer among non-smokers. EPA recommends fixing a home at 4 pCi/L or above and considering it from 2 pCi/L. A short-term test kit costs about $15–30. How radon zones work →
Superfund sites nearby
| Site | Status | Distance |
|---|---|---|
| JASCO Chemical Corp. Mountain View, California · EPA ID CAD009103318 | Cleaned up & deleted | 1.7 mi |
| Spectra-Physics, Inc. Mountain View, California · EPA ID CAD009138488 | Active (final NPL) | 2.5 mi |
| Teledyne Semiconductor Mountain View, California · EPA ID CAD009111444 | Active (final NPL) | 2.6 mi |
| CTS Printex, Inc. Mountain View, California · EPA ID CAD009212838 | Active (final NPL) | 2.6 mi |
| Hewlett-Packard (620-640 Page Mill Road) Palo Alto, California · EPA ID CAD980884209 | Active (final NPL) | 3.0 mi |
| Intel Corp. (Mountain View Plant) Mountain View, California · EPA ID CAD061620217 | Active (final NPL) | 3.2 mi |
| Raytheon Corp. Mountain View, California · EPA ID CAD009205097 | Active (final NPL) | 3.4 mi |
| Fairchild Semiconductor Corp. (Mountain View Plant) Mountain View, California · EPA ID CAD095989778 | Active (final NPL) | 3.5 mi |
| Moffett Naval Air Station Sunnyvale, California · EPA ID CA2170090078 | Active (final NPL) | 3.9 mi |
| Westinghouse Electric Corp. (Sunnyvale Plant) Sunnyvale, California · EPA ID CAD001864081 | Active (final NPL) | 5.0 mi |
EPA Superfund National Priorities List (NPL): the country’s most serious known hazardous-waste sites, each with an EPA cleanup record (linked). Distance is measured from the ZIP center to the site’s reference point; being near a site does not by itself mean exposure — EPA site pages describe what was found and how it is being cleaned up.
What this is — and isn’t. These are records your water utility and state reported to the EPA, and the EPA’s radon map for your county. They describe the system and the area, not the water from your own tap or the air in your home. For that, read your utility’s annual Consumer Confidence Report and test: lead and radon tests are inexpensive.
Questions about 94023
Who supplies drinking water to ZIP 94023?
CWSC Los Altos Suburban (EPA ID CA4310001), a surface water (rivers, lakes) system serving about 63,559 people.
Is there lead in Los Altos, CA tap water?
The utility’s latest 90th-percentile lead result (Jan 2023) was 1.5 ppb; EPA’s action level is 15 ppb, falling to 10 ppb from 2027. Lead mostly comes from service lines and home plumbing, so the only way to know your tap is to test it.
Does Los Altos, CA water have PFAS?
PFAS were detected, with PFOA and PFOS below 4.0 ppt (highest not detected).
Has the water system in 94023 had violations?
No health-based violations reported since 2016.
Are there Superfund sites near 94023?
Active or proposed Superfund (National Priorities List) sites near the center of this ZIP code. Sites within 10 miles: JASCO Chemical Corp. (1.7 mi, Cleaned up & deleted); Spectra-Physics, Inc. (2.5 mi, Active (final NPL)); Teledyne Semiconductor (2.6 mi, Active (final NPL)).
Is radon a problem in Santa Clara?
Santa Clara is in EPA radon zone 2 (moderate potential). Predicted average indoor radon between 2 and 4 pCi/L. Test your home; many homes here exceed 4 pCi/L.