Grease Trap Requirements
Portsmouth, NH

FOG Compliance in Portsmouth, NH

Food service establishments in Portsmouth operate under a combination of federal EPA pretreatment standards, New Hampshire 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 Portsmouth, the rule is: Monthly (standard). 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 Portsmouth 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.

Portsmouth requires a dedicated FOG permit for any food service establishment generating fats, oils, and grease. The annual permit fee is 75. The permit is separate from, and in addition to, the plumbing permit required at installation.

Portsmouth 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. Annual permit renewal with proof of cleaning. 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 Portsmouth Public Works Department, Wastewater & Sewer Division, 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.