Why is there grease in my sewer line after the interceptor?

1. 1The device is overdue. Phoenix says most interceptors stop working well at 25 percent full, and Chandler says that if grease is seen leaving a device, the cleaning frequency must increase.
2. 2Parts are missing or the tank has rotted. Phoenix inspectors check for missing parts and tanks that have rotted out. A broken baffle or lid lets grease pass.
3. 3Emulsifiers or enzymes. Chandler explains that these products emulsify FOG only temporarily, until it congeals again farther down the pipe, generally in the city sewer. Phoenix prohibits them.
4. 4Hot water. Scottsdale's plumbing code prohibits discharging wastewater hotter than 140 degrees F to any interceptor. Ask your city what limit applies before sending hot dish machine water to the device.
5. 5A fixture that skips the device. Phoenix's plan review requires every grease-bearing fixture to route to the device, and Tempe inspectors check that floor sinks, mop sinks, floor drains and dishwashers are plumbed to it.

• Have the device fully pumped, and watch it. Phoenix suggests witnessing the cleaning so you can look for damaged or missing parts.
• Ask the plumber to trace any fixture that may bypass the device.
• Stop using additives, and check water temperatures at the dish machine.
• Then have the downstream line jetted and camera-checked to clear what is already coated.

Phoenix's manual says keeping FOG out of the plumbing from the start reduces the likelihood of a grease blockage in or downstream from your facility. That cuts the need for routine jetting, the chance of shutting down for an emergency overflow, and the chance of causing damage downstream that you could be back billed to fix. Chandler says the owner of the device assumes the costs of cleaning, maintenance and repairs.

See what happens during a grease trap cleaning, pumping vs cleaning vs jetting, and who is responsible for the sewer line in Phoenix. Our hydro jetting page covers the line-cleaning step.