Pipe the ice machine's drain to a floor sink, trapped standpipe or floor drain through an air gap, never as a direct connection to the sewer line. Maricopa County's guide calls for a minimum 1-inch air gap; Hoshizaki's manual calls for 2 inches. Where both apply, meet the larger one.
What the rule says
The 2021 International Plumbing Code, section 802.1.1, reads: "Equipment and fixtures utilized for the storage, preparation and handling of food shall discharge through an indirect waste pipe by means of an air gap." An ice bin stores ice, which is food. The FDA Food Code, which health departments use for restaurants, comes at it from the other side. Section 5-402.11 says a direct connection may not exist between the sewage system and a drain originating from equipment in which food, portable equipment or utensils are placed, with limited exceptions such as certain floor drains in refrigerated spaces.
Maricopa County's plan review guide for food establishments spells out the same idea. It names ice machines and ice bins among the fixtures that must drain through an air gap. The county guide adds: "A direct connection may not exist between the sewerage system and any drains originating from equipment in which food, portable equipment, or utensils are placed, except if otherwise required by the applicable plumbing code."
How big the air gap is
Three numbers show up, and they don't match, so use the strictest that applies.
- The IPC: section 802.3.1 says the gap between the indirect waste pipe and the flood level rim of the receptor "shall be not less than twice the effective opening of the indirect waste pipe."
- Maricopa County: its guide says indirect waste lines "require a minimum 1-inch air gap above the flood level of an approved floor sink or drain."
- Manufacturers: Hoshizaki's manual for its AM-50BAJ cuber says the drain line "should not be piped directly to the sewer system" and that an air gap of "a minimum of 2 vertical inches" must sit between the end of the icemaker drain pipe and the floor drain. Scotsman's manual for its GT and GB cube makers calls for a minimum 1.5 inch air gap where individual drains discharge to a common manifold, drain or standpipe.
If your manual says 2 inches and the county minimum is 1, use 2.
What the drain ends in
The receptor has its own rules. IPC section 802.3 says waste receptors "shall be trapped and vented and shall connect to the building drainage system." Section 802.4 requires a removable strainer or basket on most receptors, keeps them out of concealed spaces, and requires ready access. Section 802.4.1 says receptors must be sized for the maximum discharge of all the indirect waste pipes they serve and "installed to prevent splashing or flooding."
Maricopa County adds the practical limits: the vented trap on the receptor should be as close as possible to the fixture and in the same room; indirect drain lines "should not exceed 10 linear feet"; each fixture needs its own separate rigid drain line; and food service equipment sinks and mop sinks cannot receive the discharge of an indirect waste pipe. IPC 802.3 also says indirect waste piping that exceeds 30 inches horizontally, or 54 inches in total developed length, shall be trapped, with an exception for a receptor that takes only clear-water waste and does not connect directly to a sanitary drainage system. See floor sinks, floor drains and mop sinks for choosing the receptor. Scotsman's DCE33 manual says a stand pipe with a trap below it or a floor drain is acceptable.
Bin drain, sump drain and condenser water
Many machines have more than one drain. Scotsman's manual for those cube makers states that each ice maker and each ice bin must enter the drain stack through separate connections. Models with a liquid condenser that does not recirculate coolant must have a drain for each condenser, also through separate connections. It also asks for a minimum drop of 1 inch per 3-foot run, while Hoshizaki asks for a vented tee and 1/4 inch fall per foot. Follow the manual for your model.
For the DCE33's drain tube, Scotsman's manual says: "Do not connect to a drain/waste line below a trap."
The supply side and inspections
The drain is half the picture. The water supply has its own backflow rules, covered in backflow preventers for soda and ice machines. In Maricopa County, plans for a restaurant go through plan review, and its guide requires a hand sink within approximately 25 feet of all ice machines. The restaurant plumbing health inspection requirements page explains what inspectors look for.
Which edition of the plumbing code applies depends on your city. If you're installing a machine or an inspector flagged the drain, HQ does commercial plumbing across the Valley, licensed and insured, with free estimates and upfront pricing, including the floor sink and drain line.