Water Quality in Guilford, CT: 1 Violation — Grade C
Grade C · Score 55/100 · 2 water systems · Updated 2026-05-03
Guilford'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 Guilford, CT show 1 EPA violation 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 Guilford
Water quality varies across Guilford's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 06437 | C | 55 | 1 | 0 | View report → |
Water Quality Overview
Guilford, Connecticut receives a water quality grade of C with an overall score of 55 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 2 water systems serving Guilford have accumulated 1 EPA violations (all monitoring/reporting type). These violations are tracked across 1 ZIP codes serving approximately 591 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Guilford'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 Guilford water systems is 0.0033 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 74% of homes built before 1986, Guilford 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
Guilford is in EPA Radon Zone 1 (High risk). The EPA recommends all homes in Zone 1 areas be tested for radon. Radon is the second leading cause of lung cancer after smoking.
Water Systems Serving Guilford
Guilford is served by 2 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 591 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 6 enforcement actions against water systems serving Guilford. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Guilford
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 Guilford Water Systems
The following contaminants have been detected or caused violations across Guilford's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Total Coliform | Microbiological | N/A | 1 | 1 | No |
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 6 enforcement actions against water systems serving Guilford. Recent actions:
| Date | Action Type |
|---|---|
| 2025-04-09 | State Informal Action |
| 2025-03-14 | State Informal Action |
| 2025-03-14 | State Informal Enforcement |
| 2025-02-28 | State Order Extension |
| 2023-01-19 | State Informal Action |
| 2023-01-05 | State Order Action |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-04-09.
Guilford vs. Nearby Connecticut Cities
How Guilford's water quality compares to similar cities in Connecticut:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Guilford | C | 1 | 2 | 591 |
| Branford | C | 1 | 2 | 591 |
| Stamford | C | 760 | 5 | 592 |
| East Haddam | C | 11 | 5 | 603 |
Common Questions About Guilford Water
These are the most common questions residents search for about water quality in Guilford, Connecticut:
Is Guilford water hard or soft? Water hardness varies by source. Guilford's 2 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Guilford tap water? Guilford's water receives a grade of C (55/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Guilford? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Guilford vs. Connecticut Average
Understanding how Guilford compares to the broader Connecticut 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 Guilford.
ZIP Codes in Guilford
Guilford spans 1 ZIP code. The ZIP with the lowest water quality score is 06437. 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.