EPA announced their intent in this new process is to provide regulatory clarity and certainty with respect to the use of blending. Their goal is to help facilities optimize wastewater treatment during wet weather. 

At the 2018 National Water Policy Fly-in EPA Assistant Administrator for the Office of Water David Ross made this announcement to wastewater and water reuse officials, stating “There has been a lack of clarity about this issue for decades.”

Rajendra Bhattarai, Division Manager for Austin Water Utility’s environmental and regulatory services and WEF Member, explained that water and wastewater utilities have been discussing the practice of blending for three decades and he hopes the EPA’s upcoming rule can help provide direction and when and how blending can be used.  “It should not be abused, but only be used to when needed to avoid damaging the plant’s treatment systems, while protecting public health and environment,” Bhattarai said. 

Rain and snowmelt can take WRRFs offline when excess water enters the wastewater collection system and exceeds a facility's capacity to treat all incoming wastewater. WRRFs 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.  This, in turn, should allow an operator to avoid a possible shutdown or damage to the water treatment plant.

EPA also announced they will be reaching out to gather input prior to issuing a proposed rulemaking.  WEF will work to develop comments and engage with EPA on this rulemaking.  According to Ross, a proposal is expected sometime this year.  (Bloomberg Environment, 4/17/19)

For more information, visit

EPA's Municipal Wastewater page

If you have any questions, contact
WEF Senior Director Claudio Ternieden.