Weir Overflow Rate

10/28/25

“How can we measure how much wastewater passes over a weir per length?”

Clarifiers slow wastewater flow speeds to ensure suspended solids float to the bottom and clean effluent rises to the top. Weirs are built into the perimeter of clarifier outlets to ensure the exit flow stays smooth and even. The amount of flow exiting per weir length, known as the Weir Overflow Rate, determines if the system is functioning normally or if flow is too quick and potentially carrying solids. Weir overflow rate is an important variable that all environmental engineers must consider when designing and monitoring clarifiers.

Image credit: https://www.westechwater.com/