Grease Trap Requirements
St. Louis, MO

FOG Compliance in St. Louis, MO

Food service establishments in St. Louis operate under a combination of federal EPA pretreatment standards, Missouri 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 has approximately 1,002 food service establishments — every one of them subject to the rules summarized below.

Pumping frequency is the compliance rule restaurant owners interact with most often. In St. Louis, the rule is: Every 90 days minimum for standard restaurants. This places it among the strictest tier of US jurisdictions, alongside most of Houston-area and high-volume Los Angeles County restaurants. The city follows the International Plumbing Code (IPC) for trap sizing and installation. Under Section 1003.3.4, which sizes traps by drainage fixture unit counts, grease interceptors installed in St. Louis 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. The local minimum trap size is: 1,000-gallon gravity grease interceptor minimum (per 950 lbs grease capacity required).

St. Louis requires a dedicated FOG permit for any food service establishment generating fats, oils, and grease. The permit is separate from, and in addition to, the plumbing permit required at installation. Violations carry maximum penalties of $1,000+ (starting fine for first violation; escalating substantially for repeat violations) , in line with typical US municipal penalties. Fines typically escalate with repeat violations, and severe discharges that cause sanitary sewer overflows can trigger federal Clean Water Act penalties layered on top of local fines.

St. Louis 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. Ongoing MSD compliance checks; bi-annual health department food safety inspections also check grease traps. 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 Metropolitan St. Louis Sewer District (MSD), 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.