Mesa City Code 8-4-22: who needs a grease interceptor and what upkeep it takes

The section starts with who needs one. Subsection (A) says interceptors "such as grease, oil, or sand shall be provided for laundries, restaurants, service stations, auto repair shops, carwashes, and other facilities" when the City Manager or Water Resources Director decides they are necessary. The trigger is the discharge: excessive grease or oil, flammable waste, sand or other harmful ingredients. The list is examples, not a limit, because "other facilities" is in the sentence.

The rest sets the ground rules:

• (B) Approval and access. The type and capacity must be approved by the city, and the device has to be easy to reach for cleaning and inspection.
• (C) Construction. Impervious, watertight, with easily removable covers. Where bolted covers are required, they must be gastight and watertight.
• (D) Upkeep and records. The owner maintains it "in continuously efficient operation at all times" and keeps written records of "all cleaning, repair, calibration, and maintenance" at the facility for at least three years, ready for the city on request.
• (E) Size. Covered on our sizing page, including the rule that covers can't say they belong to the City of Mesa.

• Interceptor. A tank that slows kitchen or shop wastewater so grease floats and solids settle before the water reaches the sewer. Mesa's own guide shows it as a passive device: it holds the grease until someone pumps it out.
• Owner. The code says owner, not tenant. Who pays in a leased space is a lease question the code doesn't answer, so read that as a reading, not a rule.
• Continuously efficient operation. Not defined. Mesa's FOG guide for restaurants fills the gap: set a regular cleaning schedule and don't wait until the device overflows.

It covers any Mesa business that sends grease, oil or sand to the city sewer and that the city decides needs a device. In practice that starts with restaurants: the plumbing plan checklist asks every submittal to show "required grease or sand oil interceptors and locations." It does not cover a home kitchen, and a business with no grease-bearing drains has nothing to install.

A new taqueria in a strip center. The landlord's shell has no grease device. The tenant's plumber puts the interceptor on the civil and plumbing sheets, and Industrial Pretreatment reviews it before anyone digs.

A tenant takes over a former restaurant. The tank is there. The code puts the record duty on the owner, and an inspector can ask for three years of logs. If the last operator kept none, start your own on day one.

The edge case. A four-fixture kitchen with no dishwasher can use a small indoor grease trap. Add a dishwasher, or a fifth food-prep fixture, and it flips to a buried interceptor. That switch is in (E)(4) and is worked through on the sizing page.

1. 1Count the grease-bearing fixtures and decide trap or interceptor using the sizing page.
2. 2Show the device and its location on the civil and plumbing plans in your Development Services submittal (the Mesa plumbing plan checklist lists it under Civil / Site Plan and Interceptors).
3. 3Send the interceptor to Industrial Pretreatment for review before installation: 480-644-2484, industrialpretreatment@mesaaz.gov, Monday to Friday 7:00 am to 2:30 pm.
4. 4Set a cleaning schedule with a pumper and stay present while it is emptied. Mesa's guide says a company representative should watch the cleaning.
5. 5Keep every invoice and service log at the facility for at least three years.

• "Mesa requires pumping every 90 days." Section 8-4-22 has no interval. Some third-party pages quote 90 days or a 25 percent rule for Mesa, and neither appears in the section. Phoenix, Scottsdale, Glendale and Gilbert do publish intervals, so don't carry their numbers over.
• "Enzymes count as maintenance." 8-4-22 doesn't address additives. Phoenix, Glendale and Gilbert all say additives can't replace pumping, so treat them as a supplement at most.
• "The pumper keeps the records." The duty sits with the owner, on site.
• "Only restaurants need one." Subsection (A) names laundries, service stations, auto shops and carwashes too.