01The verdict: is Mendon water safe?
Mendon's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (87.3/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 501 residents using gup.
16 unresolved violations on record
EPA records show open compliance items for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 1.0 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓A flood-prone service area
10 federal disaster declarations on record. After severe weather, watch for boil-water advisories.
See the risk factors ↓Mendon's drinking water received a grade of A- (87.3 out of 100), indicating good water quality. The city's 2 water systems serve approximately 501 residents using gup.
Lead levels were measured at 1.0 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 90 violations on record, including 4 health-based violations. 16 remain unresolved.
Mendon ranks #73 out of 269 cities in Massachusetts for water quality, placing it mid-range in the state. As a small community water system, Mendon may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Mendon's water
Every contaminant flagged in Mendon, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
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. | 1.0 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Massachusetts
Cities ranked by compounds detected Cu Copper in Massachusetts
Cities ranked by 90th-percentile copper
03Mendon's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 90 violations on record, including 4 health-based violations. 16 remain unresolved.
7 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 0 ppb since 1994. Latest reading: 1 ppb (2025) — 7% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Mendon's water comes from
Mendon's water comes from groundwater under the direct influence of surface water, a designation that requires the same treatment rigor as surface water systems.
GUP
Source details for this system are limited in EPA records.
Local treatment
Treatment is regulated under the Safe Drinking Water Act.
2 systems
2 water systems, operated under local government ownership.
501 people
Residents served across Mendon's service area.
This source type is vulnerable to both surface contamination pathways and naturally occurring underground contaminants. The system is operated by local government ownership and serves approximately 501 people through 2 water systems.
| System name | PWSID | Population | Source |
|---|---|---|---|
| MENDON WATER DEPARTMENT | MA2179000 | 470 | GUP |
| MENDON HOUSING AUTHORITY | MA2179001 | 31 | Groundwater |
Water bodies near Mendon
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on Mendon's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
10 federal disaster declarations on record for Worcester County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Worcester County is in D2 (severe drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Mendon compares
Scores for nearby Massachusetts cities on one line, with the average marked.
dashed line = Massachusetts average (81/100)
Mendon scores 87.3/100 — above the Massachusetts average of 81/100. It outscores 7 of 10 nearby cities. Full Massachusetts rankings →
76.8 / 100BWorcester, MA
78.9 / 100BSpringfield, MA
82.9 / 100ABeverly, MA
87.5 / 100BCambridge, MA
81 / 100BLowell, MA
84.5 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Mendon's water — not generic advice.
A basic carbon filter still helps
Mendon's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Mendon alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Mendon, MA tap water safe to drink?
Mendon's water quality earned a grade of A- (87.3/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #73 out of 269 cities tested in Massachusetts.
What contaminants are in Mendon's water?
Lead was measured at 1.0 ppb (90th percentile). 90 violations are on record.
How is Mendon'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 Mendon?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Mendon's water come from?
Mendon's water is sourced from GUP. The city has 2 water systems serving approximately 501 residents.
What health violations has Mendon's water system had?
Mendon has 4 health-based violations on record. The most recent violation was recorded in December 2020. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 16 violations remain unresolved.
How does Mendon's water compare to other cities?
Mendon ranks #73 out of 269 cities in Massachusetts (better than 73% of state cities) and #4136 out of 15382 cities nationally (73th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.