Which Mesa businesses must have a backflow assembly? City Code 8-1-8

Section 8-1-3 is the rule: a backflow assembly "is required at every service connection" where the customer's water system poses a health, non-health or plumbing hazard, or where access is so restricted the city can't inspect. Dedicated landscape connections need one "regardless of classification as residential or commercial." Potable water can never connect directly to sewer-connected waste. Where it drains, it must go through an air gap.

Section 8-1-8 is the list. Uses that call for a reduced pressure assembly (RPA) include:

• restaurants and convenience stores
• medical and dental buildings, hospitals and assisted care
• car washes and commercial laundries
• buildings over three stories or 34 feet
• commercial or industrial buildings where one service feeds several tenants
• shell buildings, shopping centers on master meters and apartment complexes on master meters
• buildings with booster pumps, potable storage tanks, fountains or sewage ejectors
• cooling towers, boilers and chillers
• schools, colleges and veterinary clinics

Other rows use a lighter or different device: a dedicated landscape meter takes a pressure vacuum breaker (PVB), a fire sprinkler fed only by the city takes a double check (DCVA), and water trucks and tanks take an RPA or an air gap.

• RPA. A reduced pressure principle assembly, the heavy-duty device with a relief valve. It protects against both backpressure and backsiphonage.
• PVB and DCVA. Lighter assemblies for lower hazards. A PVB has to sit at least 12 inches above the downstream plumbing.
• Service connection. The point where Mesa's water meets the customer's system, so protection is generally at the meter, not at each fixture.
• Point-of-use protection. Extra protection at equipment inside the building. 8-1-3(D) lets the city require it on top of the service device.

Commercial and industrial customers on Mesa's water system, plus any home with a dedicated landscape meter. It also covers properties outside city limits that Mesa serves. It does not reach a single-family home with a standard domestic meter, unless something else on the property creates a cross-connection.

A dental office in a strip center. Medical and dental buildings are listed, so the service needs an RPA even if the suite is small.

A car wash. Car washes are listed, so the service gets an RPA at the meter. If the site also has an irrigation line, that line is protected too.

The edge case. A church has a dedicated irrigation meter. On flat ground a PVB works. On a berm where the PVB can't sit 12 inches above every downstream sprinkler line, the same customer needs an RPA.

1. 1Match every use on the property to the 8-1-8 table, or to the city's "Customers Requiring a Backflow Prevention Assembly" list linked from its backflow page.
2. 2If two or more listed uses share one service connection, plan on an RPA.
3. 3Show the assembly on the plumbing plans. The checklist requires backflow devices to be "reviewed and approved before installation": backflow@mesaaz.gov or 480-644-6462.
4. 4Pull the permit through Development Services before installing a commercial or industrial assembly, as the city's backflow page requires.
5. 5Have a Mesa-recognized tester test it and file the report. See annual testing.

• "Our building is small, so a DCVA is fine." Size isn't the test. Use decides, and most listed commercial uses are RPA.
• "The landscape meter is covered by the building's device." Dual-use meters need the landscape line isolated with an RPA or PVB in addition to the service protection.
• "The city's page says 2006 IPC." That page still mentions it. Mesa Code 4-5-1 adopts the 2024 IPC, and 8-1 is the local chapter that governs this list.