Boston, Massachusetts Tap Water Quality Report
Serving utility: Boston Water and Sewer Commission (MWRA)
Updated March 2026 • Data from EWG Tap Water Database & EPA SDWIS
High Priority Concerns
Boston tap water has 11 contaminants exceeding EWG health guidelines, including Haloacetic acids (HAA9), Haloacetic acids (HAA5)*, Total trihalomethanes (TTHMs)*. Additionally, 12 known or suspected carcinogens were detected, including Haloacetic acids (HAA9), Haloacetic acids (HAA5)*, Total trihalomethanes (TTHMs)*.
Water Provider Information
Contaminants Detected
| Contaminant | Detected Level | EWG Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Haloacetic acids (HAA9) carcinogen | 16.80 ppb | 0.06 ppb | No legal limit | Above guideline |
| Haloacetic acids (HAA5)* carcinogen | 14.70 ppb | 0.10 ppb | 60 ppb | Above guideline |
| Total trihalomethanes (TTHMs)* carcinogen | 17.20 ppb | 0.15 ppb | 80 ppb | Above guideline |
| Dichloroacetic acid* carcinogen | 11 ppb | 0.20 ppb | No legal limit | Above guideline |
| Bromodichloromethane* carcinogen | 3.25 ppb | 0.06 ppb | No legal limit | Above guideline |
| Chloroform* carcinogen | 13.10 ppb | 0.40 ppb | No legal limit | Above guideline |
| Trichloroacetic acid* carcinogen | 2.02 ppb | 0.10 ppb | No legal limit | Above guideline |
| Perfluorooctanoic acid (PFOA)* carcinogen | 0.83 ppt | 0.09 ppt | 4 ppt | Above guideline |
| Dibromochloromethane* carcinogen | 0.81 ppb | 0.10 ppb | No legal limit | Above guideline |
| Perfluorooctane sulfonate (PFOS)* carcinogen | 0.44 ppt | 0.30 ppt | 4 ppt | Above guideline |
| Nitrate* carcinogen | 0.14 ppm | 0.14 ppm | 10 ppm | Above guideline |
| Aluminum* | 4.43 ppb | 600 ppb | No legal limit | Below guideline |
| Barium* | 7.39 ppb | 700 ppb | 2,000 ppb | Below guideline |
| Bromide* | 12.20 ppb | N/A | No legal limit | Below guideline |
| Chlorate | 117.40 ppb | 210 ppb | No legal limit | Below guideline |
| Fluoride* | 0.29 ppm | N/A | 4 ppm | Below guideline |
| Manganese | 8.22 ppb | 100 ppb | No legal limit | Below guideline |
| Monochloroacetic acid* | 1.70 ppb | 53 ppb | No legal limit | Below guideline |
| Nitrite* carcinogen | 0.00 ppm | N/A | 1 ppm | Below guideline |
| Perfluorobutane sulfonate (PFBS)* | 0.13 ppt | 2,000 ppt | No legal limit | Below guideline |
| Perfluoroheptanoic acid (PFHPA)* | 0.41 ppt | 1,000 ppt | No legal limit | Below guideline |
| Perfluorohexanoic Acid (PFHxA)* | 0.51 ppt | 1,000 ppt | No legal limit | Below guideline |
| Strontium | 0.04 ppb | 1,500 ppb | No legal limit | Below guideline |
Health Context
Haloacetic acids (HAA9) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Haloacetic acids (HAA5)* carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Total trihalomethanes (TTHMs)* carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Dichloroacetic acid* carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Bromodichloromethane* carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Recommended Filtration for This Water
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Shop Hydrogen FlaskFrequently Asked Questions
Is Boston tap water safe to drink?
Boston tap water meets EPA legal standards for drinking water. However, 11 contaminants exceed stricter EWG health guidelines, and 12 known carcinogens were detected. While legally compliant, additional filtration is recommended for optimal safety.
What contaminants are in Boston water?
A total of 23 contaminants were detected in Boston tap water, including Haloacetic acids (HAA9), Haloacetic acids (HAA5)*. Of these, 11 exceed EWG health guidelines.
What's the best water filter for Boston?
For Boston tap water, we recommend a reverse osmosis (RO) system for drinking water — it removes up to 99.9% of contaminants including heavy metals, PFAS, and disinfection byproducts. For shower and bath water, a whole-home filtration system reduces chlorine and volatile organics.
Where does Boston get its water?
Boston tap water is provided by Boston Water and Sewer Commission (MWRA), serving approximately 617,594 people. For detailed source water information, contact your local utility or visit the EPA's SDWIS database.
Nearby City Water Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: March 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
