Grease Trap Requirements
Missoula, MT
FOG compliance regulations for food service establishments in Missoula, Montana.
FOG Compliance in Missoula, MT
Food service establishments in Missoula operate under a combination of federal EPA pretreatment standards, Montana 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.
Pumping frequency is the compliance rule restaurant owners interact with most often. In Missoula, the rule is: Every 90 days or when FOG reaches 25% of design capacity, whichever comes first. This aligns with the 90-day US median enforced by most major cities. 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 Missoula 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.
Missoula 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 200 . 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.
Missoula 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. Routine inspections by WRA; $50 inspection fee. 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 Missoula Wastewater Reclamation Authority (WRA), 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.
Pumping Requirements
Permits & Enforcement
Complete FOG Regulations
| Pumping Frequency | Every 90 days or when FOG reaches 25% of design capacity, whichever comes first |
|---|---|
| 25% Rule | Yes — trap must be pumped when grease and solids reach 25% of capacity |
| Permit Required | Yes |
| Maximum Fine | 200 |
| Inspections | Routine inspections by WRA; $50 inspection fee |
| Record Keeping | Required — maintain pumping logs and manifests on-site |
| Plumbing Code | Uniform Plumbing Code (UPC) |
| Ordinance Ref. | Missoula City Code Title 20; Ordinance 3442 |
| Authority | Missoula Wastewater Reclamation Authority (WRA) |
Additional Notes
All newly constructed or remodeled FSEs must install a gravity grease interceptor (GGI). Grease removal devices must be maintained by a certified grease hauler. Violations result in fines of $100-$200, civil penalties, required compliance plans, mandated installation of properly sized exterior grease interceptors, and clean-up cost liability. WRA performs routine and compliance inspections.
Last verified: — Regulations change frequently. Always verify current requirements with your local wastewater authority or plumbing inspector before making compliance decisions.
Contact Information
(406) 552-6600 or brookp@ci.missoula.mt.us
Official Sources
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