A new Environmental Protection Agency proposal aimed at eliminating “forever chemicals” in drinking water could cost local water utilities millions of dollars each, and some of that price tag is already being passed on to consumers.

The EPA’s regulation would limit a handful of PFAS — a label for the thousands of potentially harmful chemicals that don’t easily break down — in drinking water to the lowest detectable limits, 4 parts per trillion. Should the proposal pass, one study estimated annual costs to water utilities could exceed $3.8 billion, expenses that could trickle down to ratepayers.

Costs are already being levied in states that are proactively cleaning up chemicals: PFAS cleanup contributed to increasing water utility rates by 18% in Hudson, Massachusetts, and by 50% in Wellesley, Massachusetts, and it’s anticipated to raise water rates at 13% this year and another 13% in 2024 in Hawthorne, New Jersey.