An official website of the United States government.

News Releases from HeadquartersWater (OW)

EPA Announces Effort to Update Wet Weather Regulations for Wastewater Treatment Plants

Contact Information: 
EPA Press Office (

WASHINGTON  — Today, the U.S. Environmental Protection Agency (EPA) announced it will be reaching out to states, local communities, and stakeholders as the Agency begins a new rulemaking process to provide certainty surrounding the use of “blending” by wastewater treatment plants. 

“EPA is taking action on a new rule that will give municipalities much-needed clarity on blending at wastewater treatment plants,” said EPA Administrator Scott Pruitt. “We look forward to engaging with partners at the state and local levels as we work to design a rule that offers a common-sense approach to protecting public health and safely managing our nation’s wastewater.”  

Through this effort, EPA seeks to provide regulatory clarity and certainty with respect to the use of blending so that facilities can optimize wastewater treatment during wet weather, which will protect both water quality and public health in the communities they serve.

EPA will be conducting robust stakeholder outreach during the coming months to gather critical input prior to issuing a proposed rulemaking.


Rain and snowmelt can take Publicly Owned Treatment Works (POTWs) offline when excess water enters the wastewater collection system and exceeds the POTW’s capacity to treat all incoming wastewater. POTWs often manage excess wet weather flow by routing some of the incoming water around the secondary (biological) treatment units and then “blending” it back in with secondary treatment effluent for disinfection prior to discharge. Blending allows an operator to avoid a possible shutdown or damage to the water treatment plant. 

For more information, visit