Is Henniker, NH Tap Water Safe to Drink?
Graded B- — but Lead was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
73.8/100
waterverge.com Henniker, NH — Water Quality Report
Henniker's drinking water received a grade of B- (73.8 out of 100), indicating fair water quality. The city's 2 water systems serve approximately 3,091 residents using groundwater.
Lead levels were measured at 23.0 ppb (90th percentile), which exceeds the EPA action level of 15 ppb. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 70 violations on record, including 13 health-based violations. 10 remain unresolved.
What to know about Henniker's water
Henniker ranks #40 out of 119 cities in New Hampshire for water quality, placing it mid-range in the state.
Henniker 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.
Lead levels exceed the EPA action level of 15 ppb, which typically indicates aging lead service lines or lead solder in the distribution system. An NSF 53-certified filter is strongly recommended for drinking and cooking water.
As a small community water system, Henniker may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Henniker, NH water safe to drink?
Henniker's drinking water has significant quality concerns based on EPA testing data. With a grade of B- (73.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 3,091 residents using groundwater (wells).
Recent water quality updates for Henniker
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Henniker's water quality assessment. Grade: B- (73.8/100).
1 health-based. Contaminants: Fluoride.
Contaminants: Lead and Copper Rule.
Contaminants: E. COLI.
Federal disaster declaration (FEMA DR-3360). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4026). Hurricane event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Henniker's water supply.
Exceeds EPA action level. Lead service line replacement and point-of-use filtration recommended.
Violation history
Henniker's water system has 70 total violations on record, including 13 health-based violations. 10 remain unresolved. 1 violation was issued in the last 5 years.
Flood & environmental risk
Merrimack County has experienced 9 federally declared disasters since 1973. 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 Contoocook River, Contoocook R Bl Hopkinton Dam, Warner River, Blackwater River.
Where does Henniker's water come from?
Henniker's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 3,091 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Contoocook River (river), Contoocook R Bl Hopkinton Dam (river), Warner River (river), Blackwater River (river).
What Henniker residents can do
Recommended: NSF 53-certified pitcher or under-sink filter. This addresses the specific contaminants found in Henniker'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.
Run cold water for 30 seconds before drinking, especially in the morning. Lead and copper leach from household plumbing when water sits in pipes.
Henniker'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
Top industrial polluters within 10 miles of Henniker
Industrial polluters nearby
Reported releases to surface water by facilities near Henniker, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
OSRAM SYLVANIA PRODUCTS INC HILLSBORO, NH03244 | — | — | 6.8 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Drought conditions
D2 — severe droughtMerrimack County is currently in D2 (severe 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
Merrimack County has experienced 9 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Henniker'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. | 23.0 | 15 | ppb | Inorganic | Over Limit |
Lead level trend (90th percentile)
See how Henniker compares by contaminant
Explore where Henniker ranks among all New Hampshire cities for specific contaminants.
Water source & infrastructure
Where Henniker's water comes from
Henniker'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 3,091 people through 2 water systems.
Water bodies near Henniker
Henniker is located near 4 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Henniker
| System Name | PWSID | Population | Source |
|---|---|---|---|
| COGSWELL SPRINGS WATER WORKS | NH1121010 | 3,000 | GW |
| WOOD HILL VILLAGE | NH1123020 | 91 | GW |
How Henniker compares
Full New Hampshire rankings →Henniker's score of 73.8/100 is on par with the average of 69/100 among major New Hampshire cities. It outscores 5 of 10 nearby cities.
Nearby cities
View New Hampshire rankings →About Henniker, NH
Learn more about your water
Guides and resources related to Henniker's water quality findings.
Explore water quality across Merrimack
Frequently asked questions
Is Henniker, NH tap water safe to drink?
Henniker's water quality earned a grade of B- (73.8/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #40 out of 119 cities tested in New Hampshire.
What contaminants are in Henniker's water?
Lead was measured at 23.0 ppb (90th percentile). 70 violations are on record.
How is Henniker'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 Henniker?
Yes — lead levels exceed the EPA action level of 15 ppb. We recommend an NSF 53-certified filter or reverse osmosis system. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Henniker's water come from?
Henniker's water is sourced from Groundwater. The city has 2 water systems serving approximately 3,091 residents.
What health violations has Henniker's water system had?
Henniker has 13 health-based violations on record. The most recent violation was recorded in July 2022. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 10 violations remain unresolved.
Is Henniker's groundwater at risk of contamination?
Henniker 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 70 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 Henniker's water compare to other cities?
Henniker ranks #40 out of 119 cities in New Hampshire (better than 66% of state cities) and #10011 out of 15744 cities nationally (36th percentile). The grade of B- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.