Water Quality Report · Updated May 12, 2026
WALTHAM WATER DEPARTMENT
WALTHAM WATER DEPARTMENT delivers tap water graded D (55/100) by TapWaterSafety.org. The utility serves approximately 65,218 residents in WALTHAM, Massachusetts using surface water (purchased). The most significant water quality concerns are: PFAS contamination; Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5)* significantly above health guideline; Chloroform significantly above health guideline. For questions, the utility can be reached at 7813143820.
Is WALTHAM tap water safe to drink?
WALTHAM WATER DEPARTMENT delivers tap water that earns a grade of D (55/100) from TapWaterSafety.org — a below-average rating, with multiple concerns including pfas contamination.
The utility serves 65,218 residents in WALTHAM, drawing from surface water (purchased).
Public testing data identifies 10 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA9), Haloacetic acids (HAA5)*, Chloroform, Bromodichloromethane, Total trihalomethanes (TTHMs)*, Dichloroacetic acid*, Trichloroacetic acid*, Dibromochloromethane, Perfluorooctanoic acid (PFOA)*, Perfluorooctane sulfonate (PFOS)*. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Quick actions for WALTHAM residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for WALTHAM WATER DEPARTMENT.
PFAS contamination
Severe concernPerfluorooctanoic acid (PFOA)*, Perfluorooctane sulfonate (PFOS)* detected. PFAS are persistent chemicals linked to cancer and immune effects with no known safe exposure threshold.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 11.9 ppb, 198x above the EWG health guideline of 0.06 ppb.
Haloacetic acids (HAA5)* significantly above health guideline
Moderate concernHaloacetic acids (HAA5)* detected at 14.7 ppb, 147x above the EWG health guideline of 0.1 ppb.
Chloroform significantly above health guideline
Moderate concernChloroform detected at 47.9 ppb, 120x above the EWG health guideline of 0.4 ppb.
Contact WALTHAM WATER DEPARTMENT
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Recommended water filters for WALTHAM
Filters matched to the specific contaminants in this water supply.
Reverse Osmosis or NSF P473 certified carbon
$80-$750Activated carbon and RO are the only technologies proven to remove PFAS at certified levels.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 55/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
11.9 ppb | 0.06 | — | — | — | — | — | 198× over |
| Haloacetic acids (HAA5)* Disinfection byproduct |
14.7 ppb | 0.1 | 60.0 | 60 | — | — | — | 147× over |
| Chloroform Disinfection byproduct |
47.9 ppb | 0.4 | — | — | — | — | — | 120× over |
| Bromodichloromethane Disinfection byproduct |
7.07 ppb | 0.06 | — | — | — | — | — | 118× over |
| Total trihalomethanes (TTHMs)* Disinfection byproduct |
17.2 ppb | 0.15 | 80.0 | 100 | — | — | — | 115× over |
| Dichloroacetic acid* Disinfection byproduct |
11.0 ppb | 0.2 | — | — | — | — | — | 55× over |
| Trichloroacetic acid* Disinfection byproduct |
2.02 ppb | 0.1 | — | — | — | — | — | 20× over |
| Dibromochloromethane Disinfection byproduct |
1.48 ppb | 0.1 | — | — | — | — | — | 15× over |
| Perfluorooctanoic acid (PFOA)* PFAS |
0.832 ppt | 0.09 | 4.0 | 100 | 100 | 0.007 | — | 9.2× over |
| Perfluorooctane sulfonate (PFOS)* PFAS |
0.44 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | 1.5× over |
| Nitrate Inorganic |
0.0804 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | Below guideline |
| Chlorate Disinfection byproduct |
106.8 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
7.18 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monochloroacetic acid* Disinfection byproduct |
1.7 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Barium* Heavy metal |
7.39 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Aluminum* Heavy metal |
4.43 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Perfluorohexanoic Acid (PFHxA)* PFAS |
0.505 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluoroheptanoic acid (PFHPA)* PFAS |
0.413 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorobutane sulfonate (PFBS)* PFAS |
0.131 ppt | 2000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.0388 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Bromide* Other |
12.2 ppb | — | — | — | — | — | — | Below guideline |
| Fluoride* Inorganic |
0.291 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Nitrite* Inorganic |
0.000554 ppm | — | 1.0 | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
WALTHAM WATER DEPARTMENT service area
This water system serves 1 community in Middlesex County, Massachusetts. Click any city for its dedicated tap water quality page.
Find the right filter for WALTHAM water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.