Does a restaurant soda machine need a backflow assembly in Gilbert?

Gilbert adopts the 2018 International Plumbing Code "as amended by subsection 10-34-2" (Town Code 10-34). The amendment list is in the Town's Technical Codes, 2020 Edition. For 608.17.1.1 it says "Amended to read as follows," and the quote above is the first sentence. The second sentence reads that the portion of the backflow preventer device downstream from the second check valve of the device, and the piping downstream from it, "shall not be affected by carbon dioxide gas."

In short, three things come out of the amended section:

1. 1A reduced pressure principle assembly, which is the RP or RPZ type with a relief valve, on the water supply connection to each dispenser.
2. 2Materials after the device: the second-check-valve side of the device and the piping after it must not be affected by carbon dioxide gas. The section does not list approved materials. Maricopa County's plan review guide, written for food establishments, says conduits and fittings between the backflow preventer and the carbonator should be a flexible line or stainless steel, and not copper or brass. That is county health guidance, not Gilbert's text.
3. 3Testing: Gilbert's backflow chapter says reduced pressure principle devices are tested at installation and at least annually (10-95(a)(3)), by a person the Town has approved in writing.

• Carbonated beverage dispenser: the amendment does not define it. Our reading is the soda fountain or bag-in-box system where water is carbonated and dispensed.
• Reduced pressure principle backflow assembly: a testable assembly with two check valves and a relief valve between them. Gilbert's text names this type, not a lighter one.
• Second check valve: the later of the two checks in the assembly, so everything on the dispenser side of it is covered by the carbon dioxide wording.
• C of O: certificate of occupancy.

Anyone installing a carbonated beverage dispenser in a Gilbert building: restaurants, convenience stores, theaters and other food service.

This amendment does not cover non-carbonated beverage dispensers. Maricopa County's plan review guide says the water supply connection to those must be protected by an ASSE 1022 backflow preventer or an approved air gap (IPC 608.17.1.2), and the Gilbert amendment text we read covers carbonated dispensers only.

A new fast-casual restaurant in a Gilbert shell. The designer puts an RP assembly on the carbonator supply and shows it on the plumbing plans. After installation, a state certified assembly tester tests it and the report sits on site for the Town's backflow inspection, which the Town requires before the certificate of occupancy.

A franchise that opens in Gilbert after opening in other cities. Its standard drawings show a lighter carbonator device that satisfies a county health review. Maricopa County calls an ASSE 1022 device the minimum and notes that local authorities may be more stringent. Gilbert names the reduced pressure assembly, so the Gilbert set of drawings changes. That is the flip: the same kitchen can pass the county's guide and still fail Gilbert's plumbing review.

The edge case: two dispensers on one line. The amendment says "each carbonated beverage dispenser." It does not say whether one assembly can serve several dispensers on a manifold. Ask the Town's plan reviewer before you order equipment.

1. 1Count the carbonated dispensers and show an RP assembly on the supply to each one on the plumbing plans, with downstream piping that carbon dioxide will not affect.
2. 2Submit through the One Stop Shop portal (OneStopShop.gilbertaz.gov), or call Development Services at (480) 503-6700.
3. 3When the install is done, have a state certified assembly tester test it and keep the report on site.
4. 4Before you call for the inspection, finish all the plumbing, including carbonators. The Town also wants the project plan, the sign-off sheet and the project manager on site. Call the Town's backflow inspection specialists at (480) 503-6714 or (480) 503-6715, and leave your name, the project name and address, the permit number and a phone number.
5. 5Put the annual test on the calendar.

• A county-approved carbonator device is enough everywhere. The county's own guide says local authorities may have stricter rules, and Gilbert's amendment names the RP assembly.
• The soda line is covered by the building's main backflow assembly. The service-line assembly in 10-92 and the dispenser protection in the plumbing code are separate requirements.
• Any piping works after the device. The amendment requires the downstream piping not to be affected by carbon dioxide gas.
• No inspection is needed for a small install. The Town says all permits require a backflow inspection before the certificate of occupancy, whether or not an assembly was installed.

Gilbert's own text governs; this page explains it.