If you live on the South Shore and follow local news, you have probably seen the headlines about PFAS, sometimes called "forever chemicals." You may have even received a notice from your town explaining that its water meets all current Massachusetts standards, while at the same time hearing that a newer, lower federal limit is on the way.
It can feel like a contradictory message. How can the same water meet today's state rules and still sit above a future federal one? The short answer comes down to timing and evolving science, not alarm. Here is a calm, plain-English look at what is actually going on, and why testing the water you drink is the most useful first step.
The Gap Between 20 and 4
For years, the Massachusetts Department of Environmental Protection (MassDEP) has set a limit of 20 parts per trillion (ppt) for the sum of six specific PFAS compounds. When this rule was adopted, it was among the stricter PFAS standards in the country. A public water system that tests below 20 ppt is compliant with the state standard today.
Science keeps moving, though. The U.S. Environmental Protection Agency (EPA) has since finalized lower federal limits, bringing the threshold for certain individual PFAS compounds (such as PFOA and PFOS) down to 4 ppt. According to the EPA, this reflects newer research on these compounds at very low concentrations.
That difference creates a middle ground. Based on public reporting, a number of South Shore systems, including parts of communities like Hingham, Scituate, and Marshfield, have at times measured somewhere between 4 ppt and 20 ppt. That range is compliant under the current Massachusetts standard, and it is also above the lower EPA figure that public systems are working toward over the next several years. Neither number says a given town's water is unsafe; they are simply two different yardsticks set at different points in time.
Why the Two Numbers Both Exist
It helps to remember what these limits are. Both the MassDEP and EPA figures are regulatory thresholds for large public water systems, built with a wide margin and meant to be measured across an entire system over time. They are designed to be protective, and they get revisited as research and treatment technology improve.
PFAS are also measured in parts per trillion, which is an extraordinarily small unit, roughly a few drops in an Olympic-sized pool. At that scale, results can vary by sample location, plumbing, and timing. That is one reason a single system-wide average and the water sitting in your own kitchen tap are not always the same thing.
What This Means for Your Home
Public water systems have until the federal compliance dates later this decade to complete the infrastructure upgrades needed to meet the 4 ppt figure. Some South Shore communities, such as Hanover and Norwell, have already committed significant funds to building advanced treatment facilities to get there. That is meaningful context, not cause for worry, and it shows the systems are actively working on it.
But you do not have to wait for those projects to finish to understand what is coming out of your own tap right now. Town reports describe the public system as a whole; they cannot tell you the exact makeup of the water flowing into your glass on a given day. Because the relevant levels are so small, the most reliable way to learn your home's own baseline is to test the water you actually drink, based on the sample collected and the contaminants tested.
Test Before You Treat
It is easy to read about forever chemicals and feel the urge to rush out and buy an expensive whole-home filter. We gently suggest taking a breath first.
Not every filter is designed for PFAS. A standard refrigerator filter or a basic water softener generally is not built for this purpose. Addressing PFAS at home usually calls for specific approaches, such as certified reverse osmosis or specialized carbon, matched to what is actually present. Spending on treatment before you know your numbers can mean paying for something you may not need, or buying the wrong tool for the job.
That is where a clear baseline helps. A PFAS Confidence Check is meant to take the guesswork out of the decision. We coordinate the sample, send it to a certified lab partner, and then walk you through your results in plain English, framed around the sample collected and the contaminants tested. No scare tactics, no confusing legal jargon, and no pressure to buy a filter.
The 4 ppt and 20 ppt numbers will keep showing up in the news for years as systems upgrade. You do not have to untangle every headline on your own. If you are curious where your own tap stands, a simple water check is a calm, practical place to begin, and it gives you real numbers to make the best choice for your household.
Ready when you are: book a water check and we will help you understand your results, one clear step at a time.