PFAS ("per- and polyfluoroalkyl substances") are a family of manufactured chemicals used for decades in nonstick, waterproof, and stain-resistant products. They break down extremely slowly in the environment, which is why they're nicknamed "forever chemicals," and why they now show up in trace amounts in water systems across the country — including Cohasset's.
Every water utility publishes an annual Consumer Confidence Report listing every contaminant it tested for, the detected range, and the legal limit. The most useful column is usually the one comparing your utility's result to the health-based goal, not just the legal limit — those two numbers aren't always the same thing.
If your home is on a private well rather than town water, none of the municipal testing above applies to you directly. Massachusetts DEP recommends private well owners test independently, since well water isn't subject to Safe Drinking Water Act monitoring requirements.
Meeting a legal limit isn't the same as being contaminant-free. MCLs are set based on what's feasible and affordable to treat at a system-wide scale — not necessarily the threshold with zero individual health risk. Households with young children, pregnant family members, or immunocompromised individuals often choose to filter regardless of a utility's compliance status.
In general terms, two filtration approaches address most of what shows up in Cohasset's testing data:
Effective against chlorine taste and odor, many disinfection byproducts, and some PFAS compounds, depending on the specific carbon media and contact time. Common in pitcher filters, faucet-mount units, and whole-house systems.
The most thorough option for PFAS, nitrates, sodium, and a broad range of dissolved contaminants. Typically installed under a kitchen sink for drinking and cooking water specifically.
A free household water test is the easiest way to figure out whether filtration makes sense for your specific home, and if so, which approach fits.