Pennsylvania is set to begin sampling drinking water across the state this month in a bid to determine whether PFAS contamination — which has closed drinking wells, raised water bills, and caused health concerns in Bucks and Montgomery Counties — is widespread.

The statewide sampling plan announced by the Department of Environmental Protection in mid-April is on track to start near the end of May, DEP officials said Thursday. To date, the state has identified 493 public water systems in Pennsylvania that are located within a half-mile of a potential source of PFAS contamination.

PFAS, also known as per- and polyfluoroalkyl substances, have been linked to cancers and other health problems. State scientists hope to gather “enough information to be able to tell whether or not we have a problem across the entire state,” Lisa Daniels, director of DEP’s Bureau of Safe Drinking Water, said.

The state will test about 360 drinking water systems statewide over one year. But officials won’t release a list of systems they’re testing, saying the sites could change during the program. The DEP will, however, release results to water suppliers and the public, likely rolling them out quarterly , Daniels said.

About 320 of the systems will be sampled for contamination. About 40 others not near likely sources of pollution will be tested for comparison.

“As we become more aware of information, whether it’s uncovering additional contaminated sites or additional sources of PFAS contamination, we need the flexibility to adjust that list,” Daniels said.

If water systems are found to have chemicals above the current EPA health advisory level of 70 parts per trillion, the DEP will notify the water supplier, require public notification for water customers, and require remediation or treatment of the water supply.

Over the past several years, PFAS contamination has caused drinking-water crises in communities from Michigan to New Hampshire. Federal and state lawmakers have urged the Environmental Protection Agency to create regulations mandating cleanup.

In February, the EPA said it would take the first step toward creating a drinking-water limit, known as a maximum contaminant level, for PFAS, but drew criticism for the pace and scope of its response. The agency will not issue a final determination on whether to create the level until the end of 2020; then the process to establish the level will take “several years,” an EPA official said at an April meeting in Abington.

Rather than wait for the EPA, Pennsylvania officials said, the state is moving forward with the sampling plan and creating its own maximum contaminant level. That should be completed within three years, but officials hope to get it done closer to two, DEP Secretary Patrick McDonnell said.

For now, the DEP doesn’t have authority to require cleanup of any water testing below 70 ppt. For systems found to have PFAS at those levels, the DEP will notify the water suppliers, “encourage them” to alert customers, and publicly post the results, Daniels said.

To date, only 175 out of 3,300 drinking water systems in Pennsylvania have been tested for PFAS. Six were found to be highly contaminated. Those tests, conducted between 2012 and 2015, could not detect smaller amounts of PFAS.

The new sampling will expand the number of systems tested and reveal the chemical even at lower levels, officials said. The plan targets systems that draw water from sources near airports, military installations, fire training schools, landfills, or Superfund sites.

That means the state testing could reveal previously undetected contamination. Some lawmakers fighting for regulation and cleanup said they hoped it would spur their colleagues to action.

“I’m encouraged by the breadth and scope of the sampling plan,” said State Sen. Maria Collett (D., Montgomery/Bucks), who has introduced legislation to address the contamination. “I expect that the findings are going to bring greater attention to the environmental and public health crisis … and that, frankly, can only lend more voices to the cause.”

If the data show widespread contamination — and the DEP gets enough scientific data to use in establishing a safe drinking-water limit for the chemicals — the agency doesn’t anticipate further testing, Daniels said. If it shows a low occurrence rate of PFAS across the state, the agency may continue sampling past the yearlong phase.

For most of the 20th century, PFAS were commonly used in plastics, firefighting foam, and products like Scotchgard and Teflon. In 2006, the major U.S. manufacturers of the chemicals agreed to phase them out by 2015, but products containing PFAS are still imported from other countries. Contamination has been found in drinking water near manufacturing plants, airports, and military installations.

Clamor has grown among area residents who want someone to move more quickly to outlaw the chemicals’ presence in drinking water and force a cleanup by the military and other polluters.

“Unfortunately, I think many communities are going to find that they are in the same situation that my community was in several years ago,” said State Rep. Todd Stephens (R., Montgomery). “If people’s drinking water is contaminated, we need to work quickly to ensure that we are getting them safe drinking water.”

Staff writer Laura McCrystal contributed to this article.