How must a Maricopa County restaurant drain its sinks, ice machines and walk-in coolers?

Under Indirect Waste Connections, the guide says to provide indirect waste lines with an air gap for ware washing sinks, dish wash machines, soda fountains, prep sinks, potato peelers, ice machines, steam tables, steam cookers, ice bins, salad bars, dipper wells, "walk-in refrigerator or freezer condensate drain lines, and other similar fixtures" (IPC 802.1). The quoted rule is the measurement: "Indirect waste lines require a minimum 1-inch air gap above the flood level of an approved floor sink or drain."

The same section sets the layout rules:

• Length. Indirect drain lines "should not exceed 10 linear feet" to an approved floor sink or drain.
• Receptor. Indirectly drained fixtures discharge to receptors, such as floor sinks, that have a vented trap placed as close as possible to the fixture and in the same room. Receptors go in accessible, ventilated areas and are sized to prevent overflows and splashing.
• Separate lines. "To avoid cross connections, each fixture will require a separate rigid drain line."
• No stacking. Food service equipment sinks or service (mop) sinks cannot receive the discharge of an indirect waste pipe. The guide's example is a food preparation sink draining into a mop sink.

Specific fixtures add their own lines:

• Three-compartment sink. An NSF-approved stainless sink with two integral drain-boards, and "All three compartments should be drained indirectly to a floor sink with an air gap." A ware washing machine cannot substitute for it.
• Food preparation sink. It is drained indirectly to a floor sink with a minimum 1-inch air gap, and garbage grinders are not to be installed on it.
• Walk-in coolers. Floor drains and sinks "cannot be installed inside walk-in refrigeration units except under the following condition (IPC §708.1)": "Trough-type floor drains may be in refrigerated processing rooms or high-moisture storage areas, such as produce coolers or meat/poultry coolers, provided that the doors to the area or room have been undercut or are swing doors." That is a separate rule from this one: "Without prior approval, floor sinks or floor drain sinks must not be installed in walk-in units." And: "Backwater valves are required for all trench and floor drains located inside the walk-in refrigerator unit unless doors have been undercut and/or swing doors have been provided." Walk-in condensate lines must drain to approved floor drains or an alternative method the Department approves, and may not run onto open ground or pavement.
• Overhead lines. Waste lines and roof drains "should not be located directly above food preparation areas, ice bins, jockey boxes, food display areas, food and equipment storage areas, utensil washing areas" and similar areas, unless separated by a method the Department approves. Overhead waste, sewer, fire suppression, beer or soda and water lines must be identified and labeled, waste lines troughed as deemed necessary, and sewer and waste lines "cannot run above potable water or beverage lines."

• Indirect waste. The guide does not define it. Read from its rules, it is a drain that ends in the air above a receptor instead of connecting directly.
• Air gap. The guide measures it "above the flood level of an approved floor sink or drain" and sets the minimum at 1 inch.
• Floor sink versus floor drain. The guide shows the two in its Figure 21 and treats both as approved receptors; it does not define them in words.
• Trough-type floor drain. The style the guide allows in refrigerated processing rooms or high-moisture storage areas, such as produce coolers or meat/poultry coolers, with undercut or swing doors.

Restaurants and other food establishments whose plans Maricopa County Environmental Services reviews. The guide also says the IPC as adopted by the Board of Supervisors and amended by the county Local Additions and Addenda is the plumbing code to follow for unincorporated establishments.

The walk-in rule has an exception the guide states in full: trough-type floor drains in refrigerated processing rooms or high-moisture storage areas, such as produce coolers or meat/poultry coolers, when the doors are undercut or swing doors. The guide also says walk-in units "are not to be confused with refrigerated food processing rooms" and sends readers to its Refrigerated Processing Rooms section.

A kitchen build-out. The plan shows the ice machine, the dish machine and the prep sink each dropping into its own floor sink, with the air gaps drawn and labeled. The reviewer sees that nothing is cross-connected and signs off.

A drain that fails the check. To save a trench, the plumber ties the ice machine and the three-compartment sink into one drain line. The guide wants a separate rigid line for each fixture, so that run is redrawn.

The edge case. A produce cooler wants a floor drain. The guide names "produce coolers or meat/poultry coolers" as high-moisture storage areas where trough-type floor drains may be installed, provided the doors are undercut or swing doors. If the doors are neither, the trough drain is not allowed. Separately, the guide says floor sinks or floor drain sinks must not be installed in walk-in units without prior approval, so a trough drain does not open the door to a floor sink. The door type decides the trough-drain answer.

1. 1Count every fixture and machine on the equipment schedule that drains, and mark which need an indirect connection.
2. 2Draw each indirect line separately to a floor sink or drain, 10 feet or less, with the air gap shown.
3. 3Put the receptors where they can be reached and ventilated, with a trap near the fixture in the same room.
4. 4Check for waste lines over food areas, and label and trough any that cannot be moved.
5. 5For walk-ins, decide the room type first, then the drain: condensate to an approved drain, or a refrigerated processing room or high-moisture storage area with trough drains and undercut or swing doors.
6. 6Submit the plan set through the Maricopa County Permit Center. The guide's Plan Review Steps say to complete the Plan Review Application, provide the supporting documents and pay the application fees there, and the Permit Center page says "All new permit and plan applications will be submitted through Permit Center."
7. 7Pay the plan review fee on the county fee schedule: $728 for an eating and drinking establishment with 0-9 seats, $885 for 10 or more (MCEHC Chapter I Fee Schedule, Rev 08/19/2026, page 28). Expedited plan reviews are assessed at two times the flat fee.
8. 8Apply at least 6 to 8 weeks before construction starts, which is the guide's recommendation. The guide says "Construction shall not commence unless the required plans have been approved." The full submittal list and the plumbing schedule are on the plan approval page.

• Myth: One drain line can serve everything. The guide says each fixture will require a separate rigid drain line.
• Myth: The mop sink is a handy dump spot. The guide says a mop sink cannot receive the discharge of an indirect waste pipe. Mesa's code lets a point-of-use RPA relief drain end at a mop sink, which is a different case, so check the local rule before generalizing.
• Myth: Condensate can run outside. The guide bars condensate lines from running onto open ground or pavement.
• Myth: Every cooler can have a floor drain. The guide's exception covers trough-type drains in refrigerated processing rooms or high-moisture storage areas such as produce and meat/poultry coolers, and only with undercut or swing doors.