Water Quality in Duncans Mills, CA: 3 Violations — Grade B
Grade B · Score 84/100 · 1 water system · Updated 2026-05-03
Duncans Mills's water is mostly safe. Minor violations exist but are primarily monitoring-related.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Drinking water compliance data for Duncans Mills, CA reflects 3 EPA violations — details in the grid below.
Water Quality by ZIP Code in Duncans Mills
Water quality varies across Duncans Mills's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 95430 | B | 84 | 3 | 0 | View report → |
Water Quality Overview
Duncans Mills, California receives a water quality grade of B with an overall score of 84 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 1 water system serving Duncans Mills have accumulated 3 EPA violations (all monitoring/reporting type). These violations are tracked across 1 ZIP codes serving approximately 82 people.
What Grade B Means
A grade of B indicates good compliance with EPA drinking water standards. While not perfect, Duncans Mills's water systems meet the vast majority of federal requirements. Minor violations may exist but typically relate to monitoring or reporting rather than health-based standards.
Lead Levels
The average 90th percentile lead level across Duncans Mills water systems is 0.0040 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 59% of homes built before 1986, Duncans Mills has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Water Systems Serving Duncans Mills
Duncans Mills is served by 1 community water system regulated under the Safe Drinking Water Act. These systems collectively serve approximately 82 people across 1 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 4 enforcement actions against water systems serving Duncans Mills. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Duncans Mills
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
EPA Enforcement History
The EPA and state regulators have taken 4 enforcement actions against water systems serving Duncans Mills. Recent actions:
| Date | Action Type |
|---|---|
| 2024-02-26 | State Order Extension |
| 2022-03-11 | State Filed Judgment |
| 2022-03-02 | State Filed Judgment |
| 2021-03-24 | State Filed Suit |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2024-02-26.
Duncans Mills vs. Nearby California Cities
How Duncans Mills's water quality compares to similar cities in California:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Duncans Mills | B | 3 | 1 | 82 |
| Alleghany | B | 0 | 1 | 82 |
| Encino | F | 72 | 1 | 82 |
| Monte Rio | D | 0 | 1 | 82 |
Common Questions About Duncans Mills Water
These are the most common questions residents search for about water quality in Duncans Mills, California:
Is Duncans Mills water hard or soft? Water hardness varies by source. Duncans Mills's 1 water system uses a single source. Check your ZIP code report for specific hardness data.
Can I drink Duncans Mills tap water? Duncans Mills's water receives a grade of B (84/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Duncans Mills? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Duncans Mills vs. California Average
Understanding how Duncans Mills compares to the broader California average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Duncans Mills.
ZIP Codes in Duncans Mills
Duncans Mills spans 1 ZIP code. The ZIP with the lowest water quality score is 95430. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
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
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.
Frequently Asked Questions
Your Water is Safe — Here's How to Keep It That Way
Grade B is excellent news. Here's what proactive homeowners do to maintain water quality:
Annual Water Testing
EPA recommends annual testing even with clean water. Home test kits: $20-$50. Catches changes before they become problems.
Maintenance Filtration
A basic carbon filter removes chlorine taste and catches emerging contaminants like PFAS that aren't yet fully regulated.
Plumbing Check
Even safe city water picks up lead from home pipes. If your home was built before 1986, a one-time pipe inspection is recommended.