Willingboro Municipal Utilities Authority officials told at least 100 concerned residents at a virtual meeting Wednesday night that their drinking water is safe and that a well where a high level of a “forever chemical” was found has been shut down.

The authority notified residents earlier this month that a chemical compound, PFOS, was detected at 15 parts per trillion based on a running annual average. The state allowable maximum is 13 ppt. It advised people with compromised immune systems, those who are pregnant or have infants, and the elderly that they may be at higher risk than others and “should seek advice from your health-care providers about drinking this water.”

However, MUA officials said that the letter was a “template” and sought to reassure residents that the situation is under control.

“I’ve been fielding calls all day,” said Diallyo Diggs, the MUA’s acting executive director. “The first biggest question I’ve been asked today, and I want to get to it first is: Is your water safe? Yes, your water is safe to drink, to take showers with, bathe with, wash your clothes with.“

Diggs said the issue stemmed from a Nov. 8 notice the MUA received that lab tests showed the high level of PFOS in one of its six wells. This year marks the first full year the state has been monitoring water suppliers for compounds in the family of per- and polyfluoroalkyl substances known collectively as PFAS.

PFOS is within that family. Because the compounds do not break down in the environment and human body, environmentalists often refer to them as “forever chemicals.”

Diggs said the tests were conducted at three different distribution points within the system.

“When the WMUA got notice of a violation of the PFOS standards in November, we began to take action,” Diggs said. By Nov. 30, the single well where the high level was found was shut down. Water coming from the other wells was below the limit, he said.

“No other water from that [closed] well is entering the system,” Diggs said. “And that’s why we can speak with confidence at this point that your water is safe to drink.”

The well is undergoing a $5 million upgrade to filter out PFAS that is likely to take 17 months.

Diggs said the letter, which was sent to the state Department of Environmental Protection, posted online, and mailed to residents, was a “template,” suggesting it might have sounded alarmist.

PFOS was used widely in metal plating and finishing as well as in firefighting foams, stain-resistant coatings for upholstery and carpets, water-resistant outdoor clothing, and greaseproof food packaging. Major sources in drinking water include discharges from industrial facilities and places where firefighting foam was routinely used, such as military bases. Because it was so widely used, officials said they couldn’t pinpoint the source of the well contamination in Willingboro.

The compounds are associated with health issues with the immune and endocrine systems and also affect cholesterol levels. But the effects are not yet fully known.

Willingboro is one of South Jersey’s largest majority-Black communities. And some residents were skeptical of the MUA, citing environmental injustice examples, such as in Flint, Mich.

In a 2013 cost-cutting measure, Michigan’s then-governor agreed to temporarily pump water from the Flint River until a new water pipeline could be built. However, the river water was never treated properly, causing lead to leach from drinking-water pipes inside homes.

Willingboro residents also complained that they had never received the letter and only heard of it from friends or media, which also made them suspicious. Officials said they had no control over the mail.

Officials also explained that the staff of the MUA is composed mostly of Willingboro residents and said it also serves neighboring Westampton Township, which is majority white. In addition, they said many other communities are just beginning to grapple with the PFAS issue, since the state’s new standards are much tougher than federal recommendations.