The chemicals are not among the 90-odd contaminants regulated by the Environmental Protection Agency under the Safe Drinking Water Act, so federal law does not require water utilities to test for them. But communities nationwide, many near military bases, have discovered levels of PFAS in their water hundreds, sometimes thousands, of times higher than the advisory level recommended by the agency.

As required by federal law, the Department of Defense has, and continues to, conduct cleanup actions at sites where PFAS was found, Chuck Prichard, spokesperson for the DOD, said.

"The Department remains committed to the health and safety of our men and women in uniform, their families, and the communities in which we serve," he added.

But overall federal response to the contamination problem has been slow, said Linda Birnbaum, former director of the National Institute of Environmental Health Sciences, a division of the National Institutes of Health.

Early this year, the EPA announced its plan to address PFAS contamination, including proposing regulatory determinations for two of the most common PFAS chemicals. This month, Congress dropped several key provisions from the National Defense Authorization Act that would have forced tighter regulation and cleanup of the chemicals.

"We see effects on liver, kidney, development, pregnancy, heart," Birnbaum said. "I think that’s where many people are frustrated. Where there’s pretty much growing, and I’d say fairly clear evidence of harm, EPA doesn’t have the flexibility to move rapidly."

Stanton agrees.

"We’ve heard about the action plan of the EPA," Stanton said. "In the meantime, we have millions of people that are drinking water that could be contaminated with a whole host of chemicals. Action is not coming fast enough."

‘Guinea pigs’

PFAS is a family of chemicals defined by the presence of one or several carbon-flourine bonds, the strongest chemical bond in nature. The chemicals, which have a unique ability to repel water, grease and other substances, have been used in a variety of products since the 1940s, including Teflon cookware and Scotchgard. They are also a key ingredient in firefighting foam, used by the DOD since at least the 1970s.

That foam is the suspected source of PFAS contamination discovered on bases and surrounding communities, including at least 401 sites on active and former bases where the chemicals were released or a suspected discharge occurred. The military has launched an effort to clean up the contamination — a task expected to cost about $2 billion.

According to Prichard, the DOD spokesperson, the foam is “currently the only product that meets military specifications to quickly control fire so that human lives can be saved.”

But, he added, DOD now only uses it to respond to emergency events, and no longer uses it for land-based testing and training. The DOD has also invested in research to develop alternatives that do not contain any form of PFAS.

In Pennsylvania, tests commissioned by the military and performed by the EPA in 2014 revealed widespread PFAS contamination near the Naval Air Station Joint Reserve Base Willow Grove and the Naval Air Warfare Center in Warminster, which was shuttered in 1997 after being declared a Superfund site. One well topped off at 2,740 ppt (parts per trillion) — 39 times the limit of 70 ppt recommended by the EPA. Groundwater near the Willow Grove base was found to have PFAS at 329,500 ppt. Tests of the soil revealed PFAS levels at 98,000 parts per billion.

The contamination affected about 85,000 residents in Bucks and Montgomery counties, where many residents get their water from private wells on their property.

Just like a neighbor down the street, Lori Cervera, 52, was diagnosed with kidney cancer in 2014. Shortly after, tests revealed high levels of PFAS in her well. She and her family drank bottled water for two years before the DOD paid to switch her household to public water.

"My kids played in the pool," Cervera said. "When my grandchildren were babies, I made them bottles with it. I’m so worried that it could have harmed my kids."

Lori Cervera sits at home with her dogs in Horsham Township, Pa. Cervera was diagnosed with kidney cancer, shortly before tests revealed PFAS contamination in her well. "Someone needs to be held accountable," she said. "You hear a lot of words, but you've never heard anybody apologize." Hannah Rappleye / NBC News

Certain types of PFAS have been linked to serious and adverse health effects in humans and animals, including birth defects, some cancers and other conditions, according to medical studies and federal agencies like the CDC.

"The stakes are the life and health of everyone who drinks water," said attorney Mark Cuker. Cuker, who also lives near the bases and represents several local families exposed to PFAS. He has sued the U.S. Navy to compel it to pay for blood testing and medical monitoring of affected residents. "Some people are going to get sick because nothing is being done."

According to reports, the DOD knew of the potential hazards to human health posed by firefighting foam since at least the 1990s. Records uncovered during litigation show that chemical companies that manufactured PFAS, including 3M and DuPont, were also aware early on of the danger.

"It's pretty much that we were guinea pigs," Cervera said. "It was, ‘Let's see what happens.’"

As it has elsewhere across the country, the DOD has made local remediation efforts, including providing filters, funding public water hookups for some well owners, and monitoring public and private water sources, among other actions. It also established a task force dedicated to the issue.

According to the DOD’s Prichard, after performing inspections of sites with known or suspected releases of PFAS, the department took "quick action to address drinking water" and lower PFAS concentrations below 70 ppt, the nonenforceable advisory level set by the EPA.

But in order to fill the gap, local officials were forced to embark on a multimillion-dollar effort, funded by state grants and surcharges paid by residents, to remove all traces of PFAS from the drinking water.

In response, Grosse and Stanton founded the Buxmont Coalition for Safer Water, a grassroots organization pushing for cleanup and monitoring of residents who, they say, continue to cope with the exposure.

Runoff from the Willow Grove base still seeps into creeks. Residents fish in a pond that was once filled with white foam. Initial tests of a small number of residents — about 200 — found high levels of PFAS in the bloodstream of those who lived near the base. The military paid to connect households to public water if they had contamination above the EPA's advisory level. But some homes had less, and so were not eligible for military cleanup.

There are also the tragedies that hit their own families. Months after Grosse’s father died from cancer, she was diagnosed with Stage 4 melanoma. Her daughter was born without a set of adult teeth.