The Pentagon is facing global bill of at least $2 billion — and likely more ? to clean up groundwater and drinking wells contaminated by years of seepage from the military’s firefighting foams. It has already paid several hundred million dollars to install filters and provide bottled water to affected areas.

Behind the scenes, however, the Pentagon has worked to convince Congress and the administration to support new contamination standards that could save the Pentagon billions — potentially at the expense of public health.

Right now, more than 126 military installations or sites and their surrounding communities have either wells or groundwater sources that contain dangerous levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), chemical compounds tied to birth defects and cancers. The chemical compounds were part of the military’s firefighting foam for decades and continued to be used as recently as last year.

In 2016, the Environmental Protection Agency issued a health advisory that recommended that water sources contain no more than 70 parts per trillion of the compounds. However, the EPA’s advisory is not law, so neither the Pentagon nor any other municipality is required to meet the 70 ppt standard. Since 2016, however, DoD has voluntarily been providing bottled water and filters to areas where exposure exceeds the 70 ppt limit.

But the Pentagon also would like to see a national standard set — at levels higher than 70 ppt, according to Sen. Tom Carper, D-Del. Over the last year DoD has worked along with NASA and the Small Business Administration to push “for the adoption of a much higher 400 ppt clean-up standard and 1200 ppt emergency level,” Carper said, a standard that would allow much higher exposure in public water sources. The Pentagon’s effort was first reported by The New York Times.