Commercial and HOA Irrigation Backflow Testing

A PVB is the simpler assembly, and it's only allowed when the landscape system plays by four rules. Arizona's backflow rule, A.A.C. R18-4-215(E)(2)(d), lists them:

1. 1The water past the assembly is used for irrigation only.
2. 2The PVB is installed per the manufacturer's specifications.
3. 3The irrigation system is designed and built so it can't create backpressure.
4. 4No chemicals, fertilizers or pesticides are injected into the water.

Miss any one and the rule says an RP is required. That last one catches more commercial sites than you'd think. A fertilizer injector added to a business park's controller turns a PVB site into an RP site, and Phoenix and Mesa say so again in their own codes.

A PVB protects against back-siphonage only. Water sitting in pipes above it can press back on it, and a PVB is not built for that backpressure. So each city sets a height test:

• Phoenix requires an RP when the system has "elevated areas which are higher than six inches below the PVB" (City Code 37-144).
• Mesa requires an RP when a PVB "cannot be at least 12 inches higher than all downstream plumbing" (City Code 8-1-8).

Picture a retail center with the PVB at the street and a landscaped berm or raised planter behind it. If any head or drip line on that berm sits higher than the city's limit, the PVB is the wrong device, even if it passes its test every year. A passing test means the parts work. It doesn't mean the assembly fits the site.

Phoenix also requires an RP when the irrigation system has multiple services, and Scottsdale does the same for a looped system fed by more than one service connection. Large HOA common areas often run that way.

Each required assembly gets a certified test at least once a year, and again after installation, relocation or repair. For a PVB, the tester checks that the check valve holds and that the air inlet opens when pressure drops. For an RP, it's both check valves and the relief valve.

Good news for property managers: an irrigation test doesn't touch domestic water. Only the landscape line behind the assembly goes dry while the tester works, so the test can run during business hours. After a repair, the retest clock depends on the city. Gilbert says a recognized tester must retest "immediately" and submit the report. Mesa allows up to 24 hours for the retest after any overhaul, repair or replacement, and the test record is due within seven calendar days (City Code 8-1-11(I) and (J)). Our backflow assembly repair page covers what happens when one fails.

The customer on the landscape water account carries the duty. For an HOA, that's usually the association for common areas. For a retail center or business park, it's usually the owner, with the property manager booking the test. Mesa removes any doubt for small properties: every dedicated landscape connection needs service protection, residential or commercial (City Code 8-1-3(E)). Our FAQ on HOA common-area irrigation testing goes through the board's side of it.

• The site fails the four conditions. Testing a PVB that should be an RP keeps you out of compliance. That's a backflow assembly replacement with a permit.
• The irrigation runs on reclaimed, canal or well water. Then the drinking water service needs an RP or air gap. See backflow for reclaimed water sites.
• It's a valve-box anti-siphon valve with no test cocks. Without test cocks there's nothing for a gauge to connect to, so it can't be tested.
• The controller or a leak is the problem. A sprinkler zone that won't shut off is a valve or controller issue, not a backflow one. See why a sprinkler system won't shut off.

HQ is certified to test and certify domestic backflow assemblies, including the PVBs and RPs on landscape water, and we file the results with the city. If heads sit above the PVB or an injector has been added, expect the city to ask for an RP, and ask us for a free estimate on the swap.

You get an upfront price before work starts, and free estimates for replacements. Related: HOA plumbing, property management plumbing, commercial backflow testing and the backflow preventers topic hub.