On April 10, 2024, the US EPA announced the first legally enforceable national drinking water standards for PFAS, the so-called “forever chemicals.” The final rule was published on April 26, 2024.

The limits

  • PFOA and PFOS: 4.0 parts per trillion each.
  • PFHxS, PFNA and HFPO-DA (GenX): 10 parts per trillion each.
  • A Hazard Index for mixtures of certain PFAS.

Public water systems have until 2027 to complete initial monitoring, and until 2029 to meet the limits if monitoring shows they’re exceeded.

What it means for utilities

Meeting limits measured in parts per trillion usually means adding treatment. The common options are granular activated carbon, ion exchange and high-pressure membranes such as reverse osmosis. Each brings new vessels or skids, process piping, pumps, controls and, often, more electrical capacity.

Much of this work will happen at existing well sites and treatment plants that need to stay in service. The technology choice gets most of the attention, but tie-ins, shutdown sequencing and power upgrades are just as important to a project’s success.

Update, May 2026: EPA has proposed changes to this rule. Read the update.