Is Marlborough, NH Tap Water Safe to Drink?
Graded A- — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
86.7/100
waterverge.com Marlborough, NH — Water Quality Report
Marlborough's drinking water received a grade of A- (86.7 out of 100), indicating good water quality. The city's 2 water systems serve approximately 850 residents using groundwater.
Lead data is not currently available for this system. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 75 violations on record, including 4 health-based violations. 2 remain unresolved.
What to know about Marlborough's water
Marlborough ranks #16 out of 119 cities in New Hampshire for water quality, placing it above 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.
Water quality score
See methodology →Is Marlborough, NH water safe to drink?
Marlborough's tap water meets most EPA standards but has areas that warrant attention. With a grade of A- (86.7/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 2 water systems serve approximately 850 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: A- (86.7/100).
Contaminants: Total Haloacetic Acids (HAA5), TTHM.
Federal disaster declaration (FEMA DR-4740). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4624). Flood event — may have impacted local water infrastructure.
1 health-based. Contaminants: Coliform (TCR).
Contaminants: Consumer Confidence Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Marlborough's water supply.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Marlborough's water system has 75 total violations on record, including 4 health-based violations. 2 remain unresolved. 2 violations were issued in the last 5 years.
Flood & environmental risk
Cheshire County has experienced 10 federally declared disasters since 1986. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Ashuelot River, Ashuelot River Below Surry Mt Dam,, Ashuelot River Above The Branch,.
Where does Marlborough's water come from?
Marlborough's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 850 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Ashuelot River (river), Ashuelot River Below Surry Mt Dam, (river), Ashuelot River Above The Branch, (river).
What Marlborough residents can do
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.
Marlborough's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Superfund sites within 10 miles of Marlborough
Superfund sites nearby
Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
- TROY MILLS LANDFILL7.2 mi
Source: EPA Superfund National Priorities List
Drought conditions
D1 — moderate droughtCheshire County is currently in D1 (moderate drought) per the U.S. Drought Monitor (week of May 5, 2026). Drought can elevate disinfection-byproduct (TTHM/HAA5) levels and taste/odor issues as utilities draw from lower reservoirs.
Source: U.S. Drought Monitor, updated weekly by NDMC, USDA, and NOAA.
Flood & disaster history
Cheshire County has experienced 10 federally declared disasters since 1986. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
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 |
|---|---|---|---|---|---|
| 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. | 2.52 | 1.3 | mg/L | Inorganic | Over Limit |
Copper level (90th percentile)
Latest reading: 1.535 mg/L (1993)
EPA action level: 1.3 mg/L
See how Marlborough compares by contaminant
Explore where Marlborough ranks among all New Hampshire 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 850 people through 2 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 |
|---|---|---|---|
| MARLBOROUGH WATER WORKS | NH1481010 | 750 | GW |
| MARLBOROUGH ESTATES | NH1482010 | 100 | GW |
How Marlborough compares
Full New Hampshire rankings →Marlborough's score of 86.7/100 is above the average of 69/100 among major New Hampshire cities. It outscores 8 of 10 nearby cities.
Nearby cities
View New Hampshire rankings →About Marlborough, NH
Learn more about your water
Guides and resources related to Marlborough's water quality findings.
Explore water quality across Cheshire
Frequently asked questions
Is Marlborough, NH tap water safe to drink?
Marlborough's water quality earned a grade of A- (86.7/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #16 out of 119 cities tested in New Hampshire.
What contaminants are in Marlborough's water?
75 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 2 water systems serving approximately 850 residents.
What health violations has Marlborough's water system had?
Marlborough has 4 health-based violations on record. The most recent violation was recorded in July 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 2 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 75 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 #16 out of 119 cities in New Hampshire (better than 87% of state cities) and #4554 out of 15744 cities nationally (71th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.