After the pump-out, a plumber looks at the inlet and outlet fittings, the internal baffles, the walls, floor and ceiling, the lid and its seating, any sample box or cleanout, and the headspace used for venting. The good version ends in labeled photos and a written list of defects, not a verbal okay.
What does a plumber inspect inside a grease interceptor?
Eight things, and they all depend on the tank being empty first.
San Antonio's annual checklist is the most specific public list we found. Its inspector confirms, among other items, that the "Interceptor is completely clean and the entire contents removed during service," that sanitary tees or elbows on the inlet and outlet sides "are not clogged, loose, or damaged," that "All internal baffles are secure and in place," and that the interceptor "does not have cracks or defects (or you can see exposed steel in the walls and floor)." It also checks that any sample box or cleanout "was opened and cleaned" and that "Manhole covers are securely and properly seated after completing cleaning."
Put together, here is what the plumber is looking at:
| What | What a problem looks like |
|---|---|
| Inlet fitting or tee | Loose, cracked, clogged or missing, so incoming flow is not diverted the way the design intends |
| Outlet tee or elbow | Broken, clogged or short, so floating grease can leave with the water |
| Internal baffles | Cracked, leaning, loose or gone, so water short-circuits through the tank |
| Walls, floor and ceiling | Cracks, pitting, spalling concrete, or exposed rebar or steel |
| Lid, frame and risers | Cracked or rocking cover, damaged frame, poor seating |
| Sample box or cleanout | Buried, stuck or full of solids |
| Headspace and venting | No clear air space above the water line |
| Incoming line | Backed up or full of grease between the kitchen and the tank |
Two of those rows come straight from design guidance. The NPCA's interceptor deck says "An inlet baffle or diverter is necessary to increase the retention time and avoid short-circuiting" and "An outlet baffle or tee is necessary." It also says "There should be clear space above the water level to allow for venting." On the sewer side, it points out that "Routine cleaning of the sewer line between the establishment and the interceptor will prevent this line from plugging."
For a deeper look at the parts that fail most, see what happens when a baffle or tee breaks and why concrete interceptors corrode.
When is the right time to inspect?
Right after the pump-out, while the tank is empty. San Antonio's rule says the inspection happens "After evacuation of the interceptor," when the inspector makes "a visual observation of all portions of the interceptor." Once the tank starts filling again, the baffles and walls are underwater and covered.
Phoenix gives operators the same opening: its manual suggests you "Witness the Grease Interceptor Cleaning to ensure the pumping company is completely cleaning the interceptor," and calls it "a good time to inspect for damaged or missing parts." The pumper is already there with the lid open. A plumber who is booked for the same visit sees the same empty tank.
Because the inside of an interceptor is a confined space, anyone who climbs in needs the right crew and equipment. The checks above can be done from the surface only in part: a camera or pole shows the baffles, and a closer look at the walls may need an entry. We explain the crew side in why entering a grease interceptor takes a confined-space crew.
What should a written inspection report include?
Photos, labels and a list of defects. San Antonio's rule requires "a written report of the inspection to the Permittee that includes the labeled photographs," the plumber's "name, address and telephone number," "the date of the inspection," and "a description of any defects observed during the inspection." The photos must cover "all inlet and outlet fittings, internal baffles, walls, floor and all other internal structures." It also warns that "Blurry, completely black, or blank photos in which the structure cannot be clearly seen are unacceptable."
San Antonio's checklist is not a Phoenix rule, and nobody in Phoenix is required to use it. But it is a good standard to ask for. If a plumber tells you the baffles are fine, ask for the picture.
How does this connect to what a city inspector looks for?
A city inspector asks a shorter set of questions and does not climb in. Phoenix's manual says its inspector "will check the grease Interceptor to see if any parts are missing or if the interceptor itself has rotted out and needs to be replaced," and will check "how much grease is in the interceptor to establish if the current maintenance schedule is adequate." Our page on what a city inspector checks at a grease trap covers the visit from the city's side. A plumber's inspection is how you find the broken part before the inspector does.
Mesa's code sets the standard the parts must meet. Interceptors "shall be of substantial construction, watertight, and equipped with easily removable covers," and "When bolted covers are required, they shall be gastight and watertight." Mesa also makes the owner responsible: interceptors "shall be maintained by the owner, at the owner's expense, in continuously efficient operation at all times."
What happens with the defects it finds?
They get fixed on a deadline. San Antonio's checklist says "Deficiencies must be corrected on or before the next scheduled pump out (maximum of 90 days)." Phoenix's inspector, when a part is broken or missing, "will issue a requirement to clean, replace, repair or anything that is needed to correct the problem" with a time frame prescribed by the city. If an inspection shows the tank itself is failing, repair versus replacement is the next question.
HQ repairs and inspects grease interceptors, including baffles and inlet and outlet fittings, with a three-person confined-space crew. We do not pump; your licensed hauler does that first. Ask for the estimate and the upfront price before work starts.