Mop Sink and Floor Sink Installation in Phoenix

In most commercial buildings, one service sink. Table 403.1 of the 2024 IPC lists a service sink for restaurants, retail, schools, factories, warehouses and places of worship, one per floor in ambulatory care facilities, and none for a business or mercantile space with 15 or fewer occupants. Food establishments have a stricter test from Maricopa County: a service sink or curbed cleaning facility with a sanitary drain, hot and cold water, and convenient access for every tenant, with a sink on each floor if there is no elevator. Carrying a mop bucket up stairs does not count. The existing FAQs on whether a restaurant needs a mop sink and floor sink versus floor drain versus mop sink cover the basics.

It involves a drain, a water supply and a protected faucet. For a floor basin, leg-mounted sink or curbed tile basin, the plumber sets a trapped, vented drain to the sanitary sewer, which means opening the slab in an existing building. Hot and cold water are piped to a mixing faucet with backflow protection. Maricopa County asks for smooth, durable wall surfaces such as stainless steel, tile or FRP rather than block, and room for mop bucket storage. If the faucet has a hose thread, a vacuum breaker is required, and no valve may sit downstream of an atmospheric vacuum breaker. If the building uses chemical dispensers, a separate water line is expected, with an ASSE 1055 air-gap backflow preventer. Service sinks are exempt from Phoenix's fixture flow-rate tables, so the faucet is not limited the way a lavatory faucet is.

Treat the mop room as a plan item. Water heaters, softeners and chemical systems should not block the basin, and Maricopa County recommends 80 inches of clearance if a water heater hangs above it.

A floor sink is a waste receptor, a trapped floor-level basin that takes the drain from equipment through an air gap. Under the 2024 IPC, equipment such as dishwashers, ice machines, prep sinks and food-handling fixtures discharge through an indirect waste pipe into a receptor. The air gap must be at least twice the effective opening of the pipe. The receptor must be trapped and vented, have a removable strainer or basket, stay out of concealed spaces, and be readily accessible. Receptor size must be sized for the maximum discharge of all pipes feeding it, so one under a bank of equipment is larger than one at a single sink. Indirect waste pipe over 30 inches horizontally or 54 inches total must also be trapped. See floor sinks in commercial kitchens and floor sink backups after a grease trap.

New drain and water piping is permitted work. In Phoenix, stopping a leak is exempt, but installing new piping is not, and concealed piping may not be covered until it is inspected. That includes a trench cut in the slab for a new floor sink or mop basin. Food establishments also go through the county's plan review, so the sinks are part of the plan set; see commercial tenant improvement plumbing for how that sequence works. When the plumbing is part of a restaurant build-out, the restaurant plumbing page shows how it fits with interceptors and kitchen drains.

If a space is under 15 occupants in a business or mercantile use, Table 403.1 may not require a service sink at all, so confirm with the plan reviewer before adding one. If the real problem is a floor sink that backs up, the line is clogged and installing another receptor will not help. See commercial drain cleaning. If a floor drain smells, it may be dry; dry floor drains and sewer smell explains how a trap seal evaporates.

HQ installs and repairs mop sinks, floor sinks and the drains behind them, with free estimates, upfront pricing before work starts and licensed and insured crews. Send the floor plan or photos of the room, the type of business, and what equipment drains to the floor. Related: commercial plumbing, schools plumbing and medical and dental plumbing.