Is Los Alamos, CA Tap Water Safe to Drink?
Graded A — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
92.7/100
waterverge.com Los Alamos, CA — Water Quality Report
Los Alamos's drinking water received a grade of A (92.7 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 1,534 residents using groundwater.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 3 violations on record, including 0 health-based violations. All violations have been resolved.
What to know about Los Alamos's water
Los Alamos ranks #84 out of 694 cities in California for water quality, placing it above average in the state.
Los Alamos relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Los Alamos may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Los Alamos, CA water safe to drink?
Based on EPA testing data, Los Alamos's tap water is generally safe to drink. The water system earned a grade of A (92.7/100), meeting federal drinking water standards across key contaminant categories. The city's 1 water system serves approximately 1,534 residents using groundwater (wells).
Recent water quality updates for Los Alamos
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Los Alamos's water quality assessment. Grade: A (92.7/100).
Federal disaster declaration (FEMA DR-3592). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4683). Flood event — may have impacted local water infrastructure.
Contaminants: TTHM, Total Haloacetic Acids (HAA5).
Contaminants: Coliform (TCR).
Key contaminant findings
Based on the most recent EPA sampling data for Los Alamos's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Los Alamos's water system has 3 total violations on record, including 0 health-based violations. All violations have been resolved.
Flood & environmental risk
Santa Barbara County has experienced 10 federally declared disasters since 1983. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Zaca C Nr Buellton, Santa Ynez R A Narrows Nr Lompoc, San Antonio C A Los Alamos, Sisquoc R Nr Sisquoc, Sisquoc R Nr Garey.
Where does Los Alamos's water come from?
Los Alamos's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 1,534 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Zaca C Nr Buellton (river), Santa Ynez R A Narrows Nr Lompoc (river), San Antonio C A Los Alamos (river), Sisquoc R Nr Sisquoc (river), Sisquoc R Nr Garey (river).
What Los Alamos residents can do
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Los Alamos's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Flood & disaster history
Santa Barbara County has experienced 10 federally declared disasters since 1983. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Los Alamos's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.96 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level (90th percentile)
Latest reading: 2.030 mg/L (1996)
EPA action level: 1.3 mg/L
See how Los Alamos compares by contaminant
Explore where Los Alamos ranks among all California cities for specific contaminants.
Water source & infrastructure
Where Los Alamos's water comes from
Los Alamos's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 1,534 people through 1 water system.
Water bodies near Los Alamos
Los Alamos is located near 5 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Los Alamos
| System Name | PWSID | Population | Source |
|---|---|---|---|
| LOS ALAMOS COMMUNITY SERVICES DISTRICT | CA4210002 | 1,534 | GW |
How Los Alamos compares
Full California rankings →Los Alamos's score of 92.7/100 is above the average of 57/100 among major California cities. It outscores 10 of 10 nearby cities.
Nearby cities
View California rankings →About Los Alamos, CA
Learn more about your water
Guides and resources related to Los Alamos's water quality findings.
Explore water quality across Santa Barbara
Frequently asked questions
Is Los Alamos, CA tap water safe to drink?
Los Alamos's water quality earned a grade of A (92.7/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #84 out of 694 cities tested in California.
What contaminants are in Los Alamos's water?
Lead was measured at 0.0 ppb (90th percentile). 3 violations are on record.
How is Los Alamos's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Los Alamos?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Los Alamos's water come from?
Los Alamos's water is sourced from Groundwater. The city has 1 water system serving approximately 1,534 residents.
Is Los Alamos's groundwater at risk of contamination?
Los Alamos uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 3 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Los Alamos's water compare to other cities?
Los Alamos ranks #84 out of 694 cities in California (better than 88% of state cities) and #1143 out of 15744 cities nationally (93th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Los Alamos's small water system affect quality?
Los Alamos's system serves approximately 1,534 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 3 violations on record.