Middlesex County, Massachusetts: drinking water report. Middlesex County is the most populous county in Massachusetts and in all of New England, with about…
Middlesex County is the most populous county in Massachusetts and in all of New England, with about 1.6 million residents spanning from Cambridge and Somerville near Boston to suburbs like Framingham, Lowell, and Concord. Water sources vary widely – MWRA (Massachusetts Water Resources Authority) serves many communities from the Quabbin and Wachusett Reservoirs, while others operate independent surface water or groundwater systems.
MWRA's reservoir system provides some of the cleanest municipal water in the Northeast. The Quabbin Reservoir watershed is protected and largely undeveloped. But communities not on the MWRA system face different risk profiles. Groundwater-dependent towns in the county have documented PFAS contamination from various sources, including fire stations and industrial sites.
According to the Massachusetts DEP, 14 public water systems in Middlesex County reported PFAS detections above the state's MCL of 20 ppt (sum of six PFAS compounds) during recent monitoring. The state's aggregate approach – regulating six compounds together rather than individually – is among the strictest frameworks in the country.
The critical first step is determining whether your community receives MWRA water or operates an independent system. The answer changes your risk profile dramatically.
Check your water to see your provider and monitoring data. For groundwater communities with PFAS detections, activated carbon or reverse osmosis filters provide household-level protection. Our water filter guide explains which work best. Pull your detailed report for historical data, and visit our Massachusetts page for statewide patterns.
Drinking water is one exposure route. These federal datasets also cover Middlesex County, MA.
The EPA places Middlesex County, MA in Zone 1 - the EPA's highest-risk category, where the predicted average indoor radon level is above 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
70% of homes in Middlesex County, MA were built before 1980, and 38% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Middlesex County, MA averages 6.5 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide