Is San Miguel, CA Tap Water Safe to Drink?
Graded A+ with no contaminants above EPA limits. Here's everything we tested and how San Miguel ranks. What to do next ↓
97/100
waterverge.com San Miguel, CA — Water Quality Report
San Miguel's drinking water received a grade of A+ (97 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 2,600 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 1 violation on record, including 0 health-based violations. All violations have been resolved.
What to know about San Miguel's water
San Miguel ranks #13 out of 694 cities in California for water quality, placing it one of the best in the state.
San Miguel 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, San Miguel may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is San Miguel, CA water safe to drink?
Based on EPA testing data, San Miguel's tap water is generally safe to drink. The water system earned a grade of A+ (97/100), meeting federal drinking water standards across key contaminant categories. The city's 1 water system serves approximately 2,600 residents using groundwater (wells).
Recent water quality updates for San Miguel
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into San Miguel's water quality assessment. Grade: A+ (97/100).
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: Coliform (TCR).
Key contaminant findings
Based on the most recent EPA sampling data for San Miguel's water supply.
Well within EPA limits.
Violation history
San Miguel's water system has 1 total violation on record, including 0 health-based violations. All violations have been resolved.
Flood & environmental risk
San Luis Obispo County has experienced 10 federally declared disasters since 1973. 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 Salinas R A Paso Robles, Estrella R Nr Estrella.
Where does San Miguel's water come from?
San Miguel's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 2,600 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Salinas R A Paso Robles (river), Estrella R Nr Estrella (river).
What San Miguel 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.
San Miguel'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
Top industrial polluters within 10 miles of San Miguel
Industrial polluters nearby
Reported releases to surface water by facilities near San Miguel, ranked by pounds discharged annually.
Total reported releases to surface water: 479,976 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
MARTINEZ REFINING CO LLC MARTINEZ, CA94553 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 473,779 | 9.5 mi |
TESORO REFINING & MARKETING CO LLC MARTINEZ, CA94553 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 5,793 | 10.0 mi |
MECS INC. MARTINEZ, CA94553 | Vanadium compounds | 404 | 9.4 mi |
CALEX MFG CO INC CONCORD, CA94520 | — | — | 6.7 mi |
CEMEX CONCORD CONCORD, CA94520 | — | — | 8.2 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
San Luis Obispo County has experienced 10 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
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 |
Lead level trend (90th percentile)
See how San Miguel compares by contaminant
Explore where San Miguel ranks among all California cities for specific contaminants.
Water source & infrastructure
Where San Miguel's water comes from
San Miguel'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 2,600 people through 1 water system.
Water bodies near San Miguel
San Miguel is located near 2 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving San Miguel
| System Name | PWSID | Population | Source |
|---|---|---|---|
| SAN MIGUEL COMMUNITY SERVICES DISTRICT | CA4010010 | 2,600 | GW |
How San Miguel compares
Full California rankings →San Miguel's score of 97/100 is above the average of 57/100 among major California cities. It outscores 10 of 10 nearby cities.
Nearby cities
View California rankings →About San Miguel, CA
Learn more about your water
Guides and resources related to San Miguel's water quality findings.
Explore water quality across San Luis Obispo
Frequently asked questions
Is San Miguel, CA tap water safe to drink?
San Miguel's water quality earned a grade of A+ (97/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #13 out of 694 cities tested in California.
What contaminants are in San Miguel's water?
Lead was measured at 0.0 ppb (90th percentile). 1 violation is on record.
How is San Miguel'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 San Miguel?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does San Miguel's water come from?
San Miguel's water is sourced from Groundwater. The city has 1 water system serving approximately 2,600 residents.
Is San Miguel's groundwater at risk of contamination?
San Miguel 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 1 violation 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 San Miguel's water compare to other cities?
San Miguel ranks #13 out of 694 cities in California (better than 98% of state cities) and #99 out of 15744 cities nationally (99th percentile). The grade of A+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does San Miguel's small water system affect quality?
San Miguel's system serves approximately 2,600 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 1 violation on record.