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Review government records associated with Los Altos Hills, California.
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Check your water bill for your utility name and confirm the reporting year. See EPA’s guide to finding your annual water quality report.
Public water-system records for Los Altos Hills, CA from EPA SDWIS.
San Jose Water
Active major or public-notice drinking-water issue detected in EPA SDWIS.
Reviewed: active/open records as of Q1 2026
City-area ZIP code · Serves 1,039,920 people
Palo Alto Park Mutual Water Company
No active drinking-water issues detected in EPA SDWIS.
Reviewed: active/open records as of Q1 2026
City-area ZIP code · Serves 2,900 people
City of Santa Clara
No active drinking-water issues detected in EPA SDWIS.
Reviewed: active/open records as of Q1 2026
Purchased or imported water record · Serves 130,746 people
Data from EPA SDWIS
PFAS screening separates EPA UCMR5 drinking-water monitoring from nearby DoD PFAS investigation-site records; EPA samples shown are from Feb 2023 to Aug 2023.
Drinking Water PFAS Monitoring
EPA UCMR5 samples public water systems. These results are separate from nearby PFAS cleanup or investigation-site records.
2 PFAS sample results above EPA limits
Sample period: Apr 2023 to Aug 2023
UCMR5 results are sampled by public water system, not every household. Confirm your water provider before treating these as tap-water results for a specific address.
| Chemical | Concentration (µg/L) | EPA Limit (µg/L) | Sample date | Over Limit |
|---|---|---|---|---|
| PFOS | 0.0062 | 0.0040 | 2023-08-16 | Yes |
| PFOS | 0.0042 | 0.0040 | 2023-04-19 | Yes |
PFAS detections below EPA limits.
Nearby PFAS Investigation Sites
DoD records are nearby site investigations, not Los Altos Hills drinking-water detections. Record names come from the source database and can be broad.
No DoD PFAS investigation records shown for this report.
No health-relevant impairment records shown among the assessment records in this report.
Reviewed: source records as of 2026
NPDES permits regulate pollutant discharges into U.S. waterways. Facilities must report compliance quarterly.
No NPDES-permitted facility records with current violation flags surfaced for this city report.
Reviewed: active/open records as of Q4 2025
Data from EPA ECHO
To investigate water contamination, check the sampling locations, dates and results below. For tap water records, see Drinking water quality above.
Reviewed: source records as of 2026
Review historical EPA air pollution records, including monitoring and facility emissions where available. For current conditions, check local air quality on AirNow.
Santa Clara County
Assessment year: 2020
According to EPA, a cancer risk of 40-in-1-million means that for every 1 million people continuously exposed to these air toxics over a 70-year lifetime, an estimated 40 may develop cancer from that exposure. This is in addition to cancer risk from all other causes.
Top modeled source groups
Data from EPA AirToxScreen
EPA designations apply to a specific pollutant and federal air quality standard (NAAQS). EPA can issue a clean-data determination while a formal designation remains in effect.
San Francisco Bay Area: Ozone
NonattainmentMarginal8-Hour Ozone (2015 Standard)
Original designation: Aug 2018
Health effects (EPA): Respiratory inflammation, aggravation of asthma, reduced lung function (EPA)
San Francisco Bay Area: PM2.5
NonattainmentModeratePM-2.5 (2006 Standard)
Original designation: Dec 2009
Health effects (EPA): Cardiovascular disease, respiratory illness, premature death (EPA)
Maintenance areas
Previously nonattainment; currently meeting the standard and monitored under an EPA maintenance plan.
San Francisco-Oakland-San Jose Area
CO · Carbon Monoxide (1971 Standard)
Classification: Moderate <= 12.7ppm
Original designation: Nov 1990
Current design value: 4.9 ppm (2023-2025)
Data from EPA Green Book
EPA annual monitor summaries describe past measurements. For current air quality, see AirNow.
San Lorenzo Valley Middle School
Annual mean: 4.3 Micrograms/cubic meter (LC)
Observation year: 2025
Data from EPA AQS
Reviewed: source records as of Q4 2025
Reviewed: source query run Nov 2026
Reviewed: source query run Nov 2026
No release reports shown in this group.
Reviewed: active/open records as of 2018
Data from EPA UST Finder
No MSHA mine or extraction site records shown for this report.
Santa Clara County, CA
EPA Radon Zone Map (June 2024 release)
Santa Clara County is EPA Radon Zone 2 (moderate potential). EPA defines Zone 2 counties as having predicted average indoor screening levels between 2 pCi/L and 4 pCi/L.
Radon levels can vary from home to home, so EPA recommends testing the property to know its indoor level.
FEMA flood zones describe mapped flood hazards. Look up a specific address with FEMA.
Minimal flood hazard — outside the 1% and 0.2% annual chance floodplains.
Results use an earlier stored RMP inventory. Current EPA ECHO location coverage is unverified.
No EPA ECHO RMP facility records with a usable location matched this city report.
PHMSA tracks incidents involving natural gas and hazardous liquid pipelines. Incidents include leaks, ruptures, and explosions.
No records dated within the last 5 years surfaced for this city report.
Reviewed: last 5 years
Data from PHMSA
Health outcomes from County Health Rankings. Values shown alongside state and national averages.
Santa Clara County, CaliforniaPop. 1,870,945
County Health Rankings edition: 2024
Premature Death
Poor or Fair Health
Poor Physical Health Days
Poor Mental Health Days
Adult Smoking
Adult Obesity
Air Pollution - Particulate Matter
Drinking water violation indicator
Diabetes Prevalence
Life Expectancy
| Indicator | County | State | National |
|---|---|---|---|
| Premature Death | 3,918 | 6,373 | 7,972 |
| Poor or Fair Health | 11.7% | 15.8% | 14.2% |
| Poor Physical Health Days | 2.5 | 3.1 | 3.3 |
| Poor Mental Health Days | 4.0 | 4.7 | 4.8 |
| Adult Smoking | 7.4% | 8.8% | 15.0% |
| Adult Obesity | 18.5% | 27.8% | 34.0% |
| Air Pollution - Particulate Matter | 9.2 | 7.1 | 7.3 |
| Drinking water violation indicator | Yes | N/A | N/A |
| Diabetes Prevalence | 9.0% | 10.8% | 9.6% |
| Life Expectancy | 84.1 | 79.9 | 77.6 |
EPA testing found PFAS in water samples from San Jose Water. Results dated Feb 16, 2023 to Aug 23, 2023 include PFOS at 0.0042 to 0.0062 micrograms per liter and PFHxS at 0.0031 to 0.0055 micrograms per liter.
Check with the utility that serves your address for its testing results.
EPA drinking water records on this page list 3 violations for San Jose Water.
The EPA drinking water records available here list no violations for Palo Alto Park Mutual Water Company.
The EPA drinking water records available here list no violations for the City of Santa Clara.
Check your water bill to identify the utility serving your address. Ask that utility about current drinking water advisories.
Nearby EPA monitoring stations provide annual air quality measurements for Los Altos Hills.
The monitoring station at San Lorenzo Valley Middle School recorded an annual average of 4.3 Micrograms/cubic meter (LC) for fine particles (PM2.5) in 2025.
Download 2025 EPA annual monitor dataCurrent air quality on AirNow
The radon data for Los Altos Hills covers Santa Clara County. EPA places this area in Zone 2, with a predicted average indoor radon screening level of 2 to 4 picocuries per liter.
No Superfund or brownfield sites were returned for this city report.
The county data for Los Altos Hills reports a life expectancy of 84.1 years in Santa Clara County, California.
The figure is from the 2024 edition of County Health Rankings, a University of Wisconsin program that publishes county health statistics.
The county data for Los Altos Hills reports 3,918 years of life lost to deaths before age 75 per 100,000 residents in Santa Clara County, California. This measure adds up the years lost to early deaths and adjusts for differences in population age.
The figure is from the 2024 edition of County Health Rankings, a University of Wisconsin program that publishes county health statistics.
The county data for Los Altos Hills lists fine-particle pollution (PM2.5) at 9.2 micrograms per cubic meter in Santa Clara County, California.
The figure is from the 2024 edition of County Health Rankings, a University of Wisconsin program that publishes county health statistics.
Federal pipeline records list an incident involving Pacific Gas & Electric Co near Los Altos Hills on Aug 19, 2010. The reported release was natural gas.