D26/100
Cohasset Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 7,555 residents · Massachusetts
What's In Cohasset's Tap Water?
34
Contaminants Tested
2
Exceed EPA Limits
1
Above EPA Goals
3 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
PFOA | 0.007 µg/L | 0.004 µg/L | Over Limit |
PFOS | 0.004 µg/L | 0.004 µg/L | Over Limit |
Lead (90th percentile) | 0.002 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
2
Violations (last 5yr)
1
Unresolved
0
Health-Related
TIER 3Resolved
Surface water treatment technique failure
When: July 1, 2022 – August 15, 2022Enforcement: Formal — state order issued
TIER 3Unresolved
Missed required monitoring deadline
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: June 1, 2021 – June 30, 2021Rule: Surface Water Treatment RuleEnforcement: Formal — state order issuedVerify on EPA.gov
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
COHASSET WATER DEPT
Population Served
7,555
Water Source
Surface Water
System ID
MA4065000
Frequently Asked Questions About Cohasset Water
Is Cohasset tap water safe to drink?
Cohasset, Massachusetts tap water receives a grade of D (26/100), which is considered poor. 2 contaminant(s) exceed EPA maximum contaminant levels and 47 violation(s) are on record. Residents should consider using an NSF-certified water filter to reduce contaminant exposure.
What contaminants are in Cohasset's water?
Of the 34 contaminants tested in Cohasset's water supply, the most notable include PFOA, PFOS, Lead (90th percentile). 2 contaminant(s) exceed EPA legal limits (MCLs). 3 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Cohasset have any water quality violations?
Yes, Cohasset has 47 EPA violation(s) on record, with the most recent in 2022. Violation types include Other, MR, TT. 2 of these are health-based violations, which are the most serious category.
Do I need a water filter in Cohasset?
Based on EPA data, using a water filter in Cohasset is recommended. 2 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does Cohasset's tap water come from?
Cohasset's drinking water is sourced from surface water and supplied by COHASSET WATER DEPT. The system serves approximately 7,555 people. Surface water sources include rivers, lakes, and reservoirs.
How often is Cohasset's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Cohasset's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does Cohasset's water compare to other cities in Massachusetts?
Cohasset's water quality score of 26/100 earns a grade of D, which is considered poor. This is a concerning score that suggests significant water quality issues. Visit our Massachusetts state page to see how all cities in the state compare.
What should I do if I'm concerned about Cohasset's water quality?
If you have concerns about Cohasset's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (COHASSET WATER DEPT) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.