Water Quality in Thornton, NH: No Violations — Grade D
Grade D · Score 53/100 · 5 water systems · Updated 2026-05-03
Thornton's water has significant violations. Water testing and filtration are recommended.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Across all 5 water systems serving Thornton, NH, federal monitoring data documents zero EPA violations — no MCL exceedances, no monitoring lapses, no enforcement actions anywhere in the compliance history.
Water Quality by ZIP Code in Thornton
Water quality varies across Thornton's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 03285 | D | 53 | 0 | 0 | View report → |
Water Quality Overview
Thornton, New Hampshire receives a water quality grade of D with an overall score of 53 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
No EPA violations have been recorded for the 5 water systems serving Thornton. This is a positive indicator, though it does not guarantee the absence of all contaminants — some substances (like PFAS) are not yet fully regulated.
What Grade D Means
A grade of D indicates significant compliance issues. Thornton's water systems have accumulated violations that suggest ongoing water quality challenges. Residents should check their specific ZIP code report and consider water testing or filtration.
Lead Levels
The average 90th percentile lead level across Thornton water systems is 0.5660 mg/L — this exceeds the EPA action level of 0.015 mg/L. 1 ZIP code exceed the EPA lead action level.
With 56% of homes built before 1986, Thornton 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
Thornton is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Thornton
Thornton is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 895 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 2 enforcement actions against water systems serving Thornton. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Thornton
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 2 enforcement actions against water systems serving Thornton. Recent actions:
| Date | Action Type |
|---|---|
| 2025-01-09 | State Informal Action |
| 2025-01-09 | State Order Extension |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-01-09.
Thornton vs. Nearby New Hampshire Cities
How Thornton's water quality compares to similar cities in New Hampshire:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Thornton | D | 0 | 5 | 895 |
| New Castle | B | 1 | 1 | 910 |
| Warner | B | 3 | 2 | 878 |
| Bretton Woods | C | 0 | 1 | 875 |
Common Questions About Thornton Water
These are the most common questions residents search for about water quality in Thornton, New Hampshire:
Is Thornton water hard or soft? Water hardness varies by source. Thornton's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Thornton tap water? Thornton's water receives a grade of D (53/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Thornton? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Thornton vs. New Hampshire Average
Understanding how Thornton compares to the broader New Hampshire 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 Thornton.
ZIP Codes in Thornton
Thornton spans 1 ZIP code. 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.