Naturally occurring iron and manganese build up in older wells and pipes over decades. Flushing, fire-flow tests, main breaks, and nearby construction can all stir that sediment loose and turn tap water visibly discolored — Pembroke's Water Division calls this an aesthetic issue, not a health hazard, though it's disruptive enough that the town committed to a $75 million infrastructure plan to reduce it.
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.
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 EPA legal limits isn't the same as being contaminant-free, and in Pembroke's case, the most common household frustration (discoloration) isn't a legal contaminant issue at all — it's a mineral and infrastructure one. Different filtration approaches address different problems:
Whole-house sediment filters or dedicated iron/manganese filtration media address the discoloration problem directly, catching the mineral particles before they reach household fixtures — useful for Pembroke households dealing with recurring brown-water events.
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, and a broad range of dissolved contaminants. Typically installed under a kitchen sink for drinking and cooking water specifically.
Not sure where to start? 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.