Tempe City Code 33-105: which commercial properties need a backflow assembly?

Subsection (a) opens with the rule: "An approved backflow prevention assembly of the type specified in this section shall be the minimum installation of each service connection", and it covers connections from a fire hydrant, a temporary connection or any other water service. A table then sorts premises into four possible protections: double check, reduced pressure (RP), air gap and pressure vacuum breaker.

The table breaks down like this:

• Reduced pressure (RP): the large majority. Examples are car washes, food processing, breweries and bottling plants, commercial laundries, hospitals and mortuaries, medical and dental buildings, high schools and colleges, mobile home parks, shopping centers, film labs, plating plants, power plants and separate irrigation systems.
• Double check: four low-hazard cases. These are buildings over three stories or 34 feet, buildings with booster pumps or potable water storage, non-interconnected auxiliary water systems, and dairies and cold storage plants.
• Air gap plus RP: water trucks and hydraulic sewer cleaning equipment.
• Catch-all: any premises where a cross-connection is maintained needs RP.

Subsection (b) covers fire lines. A direct connection that does not contaminate gets a double check; contaminating connections, lines with a pump or storage tank, and lines with an auxiliary supply get RP. Subsection (c) adds that any premises where the city's water could deteriorate in sanitary quality must be protected as the department requires.

• Service connection: where the city line meets your property, usually at the meter.
• RP assembly: two check valves with a relief valve between them. It is the strongest testable assembly and it must sit above ground in Tempe.
• Low hazard / high hazard: 33-105 uses the words without defining them. Our reading: low hazard means what could flow back is a nuisance, high hazard means it could make people sick.
• Contaminating: used for fire lines and also undefined. Our reading is a connection where something other than drinking water could be pushed back into the pipe.

It covers commercial and industrial customers, multi-use properties and any residence used for something other than living. It does not apply to a single-family home used only as a home. Tempe's Environmental Services page says state rules exempt those, and that an Environmental Compliance Inspector decides case by case and puts the decision in writing.

A strip mall with a landscape line. The shopping center lands on the RP list. A separate irrigation system is its own line on the RP list, so the landscaping is not a lighter case.

A mid-rise office. Four floors puts it over the 3-story line. The low-hazard row lists a double check as the minimum. If the building also runs a chemically treated water system, that is a separate RP line in the table.

The edge case: a restaurant. Tempe's table names food processing but not restaurants. That does not mean a restaurant is exempt: the catch-all covers any cross-connection, and the Environmental Compliance Inspector can require protection in writing. The city's plan and inspection process decides.

1. 1Find your premises type in the table and note the assembly type it lists.
2. 2If you are building or changing use, put the assembly on the plans. Section 33-103 requires approval before the building permit issues.
3. 3Use an assembly from the department's approved list and install it under the Building Safety permit.
4. 4Hire a Tempe-registered tester for the first test and every annual test after it.
5. 5If Environmental Services sends a compliance notice, you have 45 days from that first notice unless the city agrees to something different. Call 480-350-2678 before the deadline, not after.

• "My building is not on the list, so I am fine." The last row covers any premises where a cross-connection is maintained, and 33-110(b) lets the Public Works Director require an assembly for any water service that threatens the public system.
• "It is a fire line, so it is the fire department's business." Fire lines are in 33-105(b) and need their own assembly.
• "RP and double check are interchangeable." The table says which one your premises needs, and an RP must go above ground.
• "Tempe's list matches Mesa's." It does not. Mesa names restaurants and convenience stores, and it treats a dedicated landscape meter differently.