Duncans Mills, CA: 3 Violations — 84/100 (2026)
1 ZIP code · 2 water systems · Updated 2026-06-03
Water utilities in Duncans Mills have maintained a consistent compliance record over recent monitoring periods — the city's above-average grade in CA reflects low violation rates and no systemic health concerns flagged in current data.
How Duncans Mills Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Duncans Mills Water
- Your city's water systems recorded 3 violations in the past 5 years.
- Average lead level: 0.004 mg/L.
- Homes built before 1986: 59% — older plumbing may contain lead solder.
- Estimated remediation: $1,200 per household.
- CDC health risk index: 11.32.
Who Supplies Your Water in Duncans Mills
2 independent water providers serve Duncans Mills, CA — 2 systems appear in federal records.
Overview
We track water quality and home safety data for 1 ZIP code in Duncans Mills, California, covering 2 community water systems serving approximately 3,082 people.
1 of 1 ZIP code (100%) have recorded EPA violations. All violations are monitoring/reporting type.
Home Safety Score
Average Home Safety Score for Duncans Mills: B (84/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Duncans Mills water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0040 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Consumer Confidence Report Rule | Reporting | 6 | 1 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 95430 | B | 3 | 0 | Sweetwater Springs Cwd - Monte Rio |
All ZIP Codes in Duncans Mills
- 95430 [B] — 3 violations
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
Health Outcomes in Duncans Mills
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Top Contaminants in Duncans Mills Water
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
Housing & Infrastructure in Duncans Mills
With 59% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
When more than half a city's housing predates the 1986 federal ban on lead solder, plumbing-era lead risk becomes a citywide concern rather than an exception. Duncans Mills's median build year of 1985 places it squarely in that category.
Over half of homes in Duncans Mills were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
Lead Exposure Risk for Children in Duncans Mills
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Older stock in Duncans Mills represents 59% of the inventory, and citywide monitoring runs at or above the federal action level — making an in-home read a standard household-level step.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Duncans Mills
The National Flood Insurance Program captures decades of claims at the local level, building a record of cumulative community flood exposure. For Duncans Mills, that record documents 75 claims and 100% of ZIP codes inside FEMA-designated flood zones. What makes those numbers relevant to water quality is the set of mechanisms flooding activates: heavy precipitation that floods treatment intake zones can introduce contaminants upstream of normal filtration; well casings in low-lying areas can be infiltrated by floodwaters carrying bacteria, sediment, and chemical residue; and distribution system pressure changes during flooding can create backflow conditions. These effects become more probable as flood frequency and magnitude increase — and the NFIP record indicates both are meaningful factors locally.
Duncans Mills has a moderate flood history with 75 FEMA claims averaging $14,331 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$1,200</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Duncans Mills, CA