Even the best-designed Grease Traps, properly installed, will fail if they are not maintained. The precise requirements for maintenance are not possible to define since conditions at each installation vary. In terms of the typical code, maintenance must be performed before the grease in the waste water, downstream from the interceptor, exceeds local limits.
While that is a simple statement to make, it is impossible for the user of a Grease Trap to determine when those limits have been exceeded. The method for determining when a Grease Trap-rated capacity has been reached is fairly simple if it is a PDI-certified. A PDI Grease Trap has a rated retention capacity equal to twice its flow rate, expressed in pounds. For example, a 35 GPM Grease Trap is rated to retain at least 70 lbs. of grease. A user may determine a cleaning schedule by measuring how much grease has been trapped over a period of time. Regardless of what the cleaning cycle is determined to be, it has been shown by actual field experience that one of the biggest obstacles to regular maintenance has been the odors usually associated with Grease Traps.