Is Dillon Beach, CA Tap Water Safe to Drink?
Graded B — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
78/100
waterverge.com Dillon Beach, CA — Water Quality Report
Dillon Beach's drinking water received a grade of B (78 out of 100), indicating good water quality. The city's 2 water systems serve approximately 1,152 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 65 violations on record, including 32 health-based violations. All violations have been resolved.
What to know about Dillon Beach's water
Dillon Beach ranks #409 out of 694 cities in California for water quality, placing it below average in the state.
Dillon Beach 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, Dillon Beach may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Dillon Beach, CA water safe to drink?
Based on EPA testing data, Dillon Beach's tap water is generally safe to drink. The water system earned a grade of B (78/100), meeting federal drinking water standards across key contaminant categories. The city's 2 water systems serve approximately 1,152 residents using groundwater (wells).
Recent water quality updates for Dillon Beach
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Dillon Beach's water quality assessment. Grade: B (78/100).
Federal disaster declaration (FEMA DR-4683). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3591). Flood event — may have impacted local water infrastructure.
1 health-based. Contaminants: TTHM.
1 health-based. Contaminants: TTHM.
Contaminants: TTHM, Total Haloacetic Acids (HAA5).
Key contaminant findings
Based on the most recent EPA sampling data for Dillon Beach'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
Dillon Beach's water system has 65 total violations on record, including 32 health-based violations. All violations have been resolved. 2 violations were issued in the last 5 years.
Flood & environmental risk
Marin County has experienced 10 federally declared disasters since 1969. 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 Walker C Nr Marshall.
Where does Dillon Beach's water come from?
Dillon Beach's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 1,152 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Walker C Nr Marshall (river).
What Dillon Beach 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.
Dillon Beach'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 Dillon Beach
Industrial polluters nearby
Reported releases to surface water by facilities near Dillon Beach, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
U.S. COAST GUARD TRAINING CENTER PETALUMA PETALUMA, CA94952 | — | — | 8.5 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
Marin County has experienced 10 federally declared disasters since 1969. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Dillon Beach'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. | 1.44 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level (90th percentile)
Latest reading: 1.440 mg/L (2000)
EPA action level: 1.3 mg/L
See how Dillon Beach compares by contaminant
Explore where Dillon Beach ranks among all California cities for specific contaminants.
Water source & infrastructure
Where Dillon Beach's water comes from
Dillon Beach'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 private ownership and serves approximately 1,152 people through 2 water systems.
Water bodies near Dillon Beach
Dillon Beach is located near 1 notable water body. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Dillon Beach
| System Name | PWSID | Population | Source |
|---|---|---|---|
| LAWSON S LANDING | CA2110008 | 946 | GW |
| ESTERO MUTUAL | CA2100519 | 206 | SW |
How Dillon Beach compares
Full California rankings →Dillon Beach's score of 78/100 is above the average of 57/100 among major California cities. It outscores 8 of 10 nearby cities.
Nearby cities
View California rankings →About Dillon Beach, CA
Learn more about your water
Guides and resources related to Dillon Beach's water quality findings.
Explore water quality across Marin
Frequently asked questions
Is Dillon Beach, CA tap water safe to drink?
Dillon Beach's water quality earned a grade of B (78/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #409 out of 694 cities tested in California.
What contaminants are in Dillon Beach's water?
Lead was measured at 0.0 ppb (90th percentile). 65 violations are on record.
How is Dillon Beach'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 Dillon Beach?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Dillon Beach's water come from?
Dillon Beach's water is sourced from Groundwater. The city has 2 water systems serving approximately 1,152 residents.
What health violations has Dillon Beach's water system had?
Dillon Beach has 32 health-based violations on record. The most recent violation was recorded in October 2021. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. All health violations have been resolved.
Is Dillon Beach's groundwater at risk of contamination?
Dillon Beach 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 65 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 Dillon Beach's water compare to other cities?
Dillon Beach ranks #409 out of 694 cities in California (better than 41% of state cities) and #8826 out of 15744 cities nationally (44th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.