Is Marlborough, CT Tap Water Safe to Drink?
Graded D — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
46/100
waterverge.com Marlborough, CT — Water Quality Report
Marlborough's drinking water received a grade of D (46 out of 100), indicating poor water quality. The city's 7 water systems serve approximately 2,005 residents using groundwater.
Lead levels were measured at 2.2 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 312 violations on record, including 19 health-based violations. 44 remain unresolved.
What to know about Marlborough's water
Marlborough ranks #114 out of 158 cities in Connecticut for water quality, placing it below average in the state.
Marlborough relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Marlborough may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 7 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Marlborough, CT water safe to drink?
Marlborough's drinking water has significant quality concerns based on EPA testing data. With a grade of D (46/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 7 water systems serve approximately 2,005 residents using groundwater (wells).
Recent water quality updates for Marlborough
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Marlborough's water quality assessment. Grade: D (46/100).
2 health-based. Contaminants: LEAD AND COPPER RULE REVISIONS.
Contaminants: Consumer Confidence Rule.
Contaminants: Consumer Confidence Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Marlborough's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Marlborough's water system has 312 total violations on record, including 19 health-based violations. 44 remain unresolved. 7 violations were issued in the last 5 years.
Where does Marlborough's water come from?
Marlborough's drinking water comes from groundwater (wells), supplied by 7 water systems serving approximately 2,005 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Housatonic River (river), Naugatuck River (river), Rooster River (river).
What Marlborough residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Marlborough's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Recommended water filters
Based on contaminants detected in Marlborough's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 2.2 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.38 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level (90th percentile)
Latest reading: 1.380 mg/L (1993)
EPA action level: 1.3 mg/L
See how Marlborough compares by contaminant
Explore where Marlborough ranks among all Connecticut cities for specific contaminants.
Water source & infrastructure
Where Marlborough's water comes from
Marlborough's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 2,005 people through 7 water systems.
Water bodies near Marlborough
Marlborough is located near 3 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Marlborough
| System Name | PWSID | Population | Source |
|---|---|---|---|
| AQUARION-MARLBOROUGH | CT0798013 | 1,348 | GW |
| CTWC - SACHEM VILLAGE CONDO | CT0792011 | 166 | GW |
| MARLBOROUGH HEALTH CARE CENTER, INC | CT0791001 | 165 | GW |
| CTWC - MARLBOROUGH GARDENS | CT0790031 | 110 | GW |
| CTWC - FOREST HOMES DIVISION | CT0790011 | 100 | GW |
| LAUREL HILL WATER ASSOCIATION | CT0790041 | 86 | GW |
| CTWC - FLORENCE LORD (MASH) | CT0791201 | 30 | GW |
How Marlborough compares
Full Connecticut rankings →Marlborough's score of 46/100 is on par with the average of 47/100 among major Connecticut cities. It outscores 6 of 10 nearby cities.
Nearby cities
View Connecticut rankings →About Marlborough, CT
Wikipedia →Shelton is a city in Fairfield County, Connecticut, United States. The population was 40,869 at the 2020 United States Census. The city is part of the Naugatuck Valley Planning Region.
Learn more about your water
Guides and resources related to Marlborough's water quality findings.
Explore water quality across Hartford
Frequently asked questions
Is Marlborough, CT tap water safe to drink?
Marlborough's water quality earned a grade of D (46/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #114 out of 158 cities tested in Connecticut.
What contaminants are in Marlborough's water?
Lead was measured at 2.2 ppb (90th percentile). 312 violations are on record.
How is Marlborough's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Marlborough?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Marlborough's water come from?
Marlborough's water is sourced from Groundwater. The city has 7 water systems serving approximately 2,005 residents.
What health violations has Marlborough's water system had?
Marlborough has 19 health-based violations on record. The most recent violation was recorded in October 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 44 violations remain unresolved.
Is Marlborough's groundwater at risk of contamination?
Marlborough uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 312 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Marlborough's water compare to other cities?
Marlborough ranks #114 out of 158 cities in Connecticut (better than 28% of state cities) and #14023 out of 15744 cities nationally (11th percentile). The grade of D reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.