Water Quality in Twain Harte, CA: 4 Violations — Grade C
Grade C · Score 60/100 · 5 water systems · Updated 2026-05-03
Twain Harte's water has moderate compliance issues. Residents in affected areas should consider filtration.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
SDWIS records for Twain Harte, CA show 4 EPA violations documented for the local water supply — these span the full range of reportable events from health-based exceedances to monitoring and reporting lapses registered with the federal program.
Water Quality by ZIP Code in Twain Harte
Water quality varies across Twain Harte's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 95383 | C | 60 | 4 | 1 | View report → |
Water Quality Overview
Twain Harte, California receives a water quality grade of C with an overall score of 60 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Twain Harte have accumulated 4 EPA violations, including 1 health-based violation. These violations are tracked across 1 ZIP codes serving approximately 3,500 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Twain Harte's water systems have some violations that warrant attention. While the water may still be safe for most people, residents in affected ZIP codes should consider additional testing or filtration.
Lead Levels
The average 90th percentile lead level across Twain Harte water systems is 0.0126 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 75% of homes built before 1986, Twain Harte 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.
Radon Risk
Twain Harte is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Twain Harte
Twain Harte is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 3,500 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 10 enforcement actions against water systems serving Twain Harte. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Twain Harte
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
Contaminants Detected in Twain Harte Water Systems
The following contaminants have been detected or caused violations across Twain Harte's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Stage 2 DBP Rule | Treatment Technique | N/A | 2 | 1 | Yes |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 4 enforcement actions against water systems serving Twain Harte. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-15 | State Order Extension |
| 2025-08-27 | State Filed Judgment |
| 2025-02-11 | State Order Extension |
| 2025-02-06 | State Filed Suit |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-15.
Twain Harte vs. Nearby California Cities
How Twain Harte's water quality compares to similar cities in California:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Twain Harte | C | 4 | 5 | 3,500 |
| Groveland | C | 6 | 2 | 3,485 |
| Nevada City | B | 1 | 4 | 3,457 |
| Borrego Springs | B | 2 | 1 | 3,429 |
Common Questions About Twain Harte Water
These are the most common questions residents search for about water quality in Twain Harte, California:
Is Twain Harte water hard or soft? Water hardness varies by source. Twain Harte's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Twain Harte tap water? Twain Harte's water receives a grade of C (60/100). There are 1 health-based violations — consider filtration.
What is the best water filter for Twain Harte? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Twain Harte vs. California Average
Understanding how Twain Harte 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 Twain Harte.
ZIP Codes in Twain Harte
Twain Harte spans 1 ZIP code. The ZIP with the lowest water quality score is 95383. 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.