What is the minimum grease trap flow rate in pounds per gallon per minute?

The minimum grease trap flow rate established in many plumbing codes and regulations, including those that apply in Massachusetts, is set at 2 pounds per gallon per minute (gpm). This standard is based on the need to effectively manage and mitigate grease buildup in plumbing systems, which can lead to blockages and foul odors if not adequately addressed.

A grease trap's performance depends on its ability to retain fats, oils, and grease (FOG) before they enter the wastewater system. The specified flow rate ensures that the grease trap can handle the expected volume of FOG generated by the connected fixtures, preventing these materials from flowing downstream and causing issues in the sewer system.

By establishing a minimum of 2 pounds per gpm, code practitioners aim to provide a balance between effectively treating wastewater while accommodating typical kitchen or industrial waste flow without exceeding the trap's treatment capacity.