The 20 parts per trillion groundwater standard for two of the most widely understood PFAS compounds — PFOA and PFOS — would help to settle any disputes between the state and owners of PFAS-polluted land over how thorough cleanups must be to protect public health.

Two-thirds of Wisconsin’s residents drink well water.

A groundwater standard would also apply directly to PFAS in bottled water. And the DNR will study the recommendation before it proposes a PFAS standard for lakes and streams that will accompany the groundwater standard through the lengthy rule-making process.

But under state law, a groundwater standard doesn’t limit the amount of PFAS that can be in municipal drinking water, even PFAS-tainted water drawn from groundwater.

Drinking water standards are set under other provisions of state law and the DNR is now considering how that could be done.

DNR officials said they will be contacting local water utilities and public health departments to ensure that they understand the health-related science behind the recommended groundwater standard so it can be taken into account when local decisions are made about drinking water tainted by PFAS.