Grease Trap Requirements
Ann Arbor, MI

FOG Compliance in Ann Arbor, MI

Food service establishments in Ann Arbor operate under a combination of federal EPA pretreatment standards, Michigan state plumbing code, and city-level FOG ordinances. Together these rules determine how grease traps must be sized, how often they must be pumped, and what happens when a restaurant falls out of compliance.

The city follows the Uniform Plumbing Code (UPC) for trap sizing and installation. Under Section 1014, which applies a fixture drainage load formula with a retention time factor, grease interceptors installed in Ann Arbor must meet minimum capacity thresholds based on the fixtures connected to them — 3-compartment sinks, dishwashers, pre-rinse stations, wok stoves, and floor drains on the cook line.

Ann Arbor enforces the 25 percent rule: grease traps must be pumped before the combined FOG and settled solids reach 25 percent of the trap's total liquid depth. Inspectors measure the depth with a sludge judge or dipstick, typically at surprise visits. Exceeding the threshold at inspection triggers a notice of violation and mandatory emergency pump-out, regardless of the scheduled pumping cycle. Establishments must maintain pumping logs, hauler manifests, and inspection reports on-site — missing records is itself a violation in most enforcement actions. Enforcement authority rests with the City of Ann Arbor Public Services / Washtenaw County Health Department, which handles permit issuance, inspections, and hauler licensing.

For a deeper explanation of the rules this city enforces, read our guides on how grease traps work and the 25/50 pumping rule.