The lease decides who pays for backflow testing. City codes don't pick landlord or tenant. They hold the water customer responsible, meaning whoever controls the water system or holds the water account, and the city sends notices and penalties to that party. Your lease then decides who books the test and who covers the cost.
Who the city holds responsible
Every Valley code we checked picks a role, not a person. Here's how each one defines it.
Phoenix. City Code 37-143 says "customer means any person that has physical control, authority or responsibility for a water system that receives water service from the City public water system." The customer "shall properly locate, install, test and maintain each backflow prevention assembly in good working condition." The customer also "shall install backflow prevention assemblies, at the customer's expense," and "must retain all records for a minimum of three years."
Look at the Phoenix definition's words "physical control, authority or responsibility." A tenant running the space has physical control. An owner has authority. Either one, or both, can be the customer in Phoenix's eyes.
Mesa. Mesa's definition names both sides of the lease. Mesa City Code 8-1-1 defines a customer as "The owner, tenant, trustee, mortgagee, receiver or occupier, whether person, corporation, firm, or municipality, of property which is connected to the public water system." It adds the person "in whose name a City water service account is established." Mesa City Code 8-1-11 then says "The testing and servicing of each backflow prevention assembly shall be performed at the expense of the customer."
Scottsdale. Scottsdale's code calls the responsible party the user. Revised Code 49-65 says "The testing and maintenance of each assembly shall be performed at the expense of the user." When an assembly is missing, Scottsdale sends written notice to the "owner or account holder," and it can install the device itself and "include the cost of such installation on the next regularly scheduled invoice to the account holder" (Revised Code 49-62).
Tempe. Tempe also calls it the user. Tempe City Code 33-101 says "The user shall at his own expense install, operate, test and maintain approved backflow prevention assemblies as directed by the department." Tempe City Code 33-107 adds that testing, maintenance and repairs "shall be made at the customer's expense."
The plumbing code lands in the same place. Phoenix's tester guidance quotes the Uniform Plumbing Code: backflow assemblies "shall be maintained in good working condition by the person or persons having control of such devices or assemblies" (TRT 00636).
| City | Who the code names | What the code says about cost |
|---|---|---|
| Phoenix | Customer: anyone with physical control, authority or responsibility for the water system | Install at the customer's expense; customer tests, repairs and keeps records |
| Mesa | Customer: owner, tenant, occupier, or the water account holder | Testing and servicing at the customer's expense |
| Scottsdale | User; notices to owner or account holder | Testing and maintenance at the user's expense; city can bill the account holder |
| Tempe | User | Install, test and maintain at the user's own expense |
| Plumbing code (via Phoenix TRT 00636) | Person having control of the assembly | Keep it in good working condition |
Where the notices go, and why that matters
The test notice goes to the water user, not to whoever the lease says should handle it. Arizona's state backflow rule says "The public water system shall notify the water user when testing of backflow-prevention assemblies is needed." Mesa's program works the same way: its backflow page says "Mesa Water Resources will send notices to regulated customers advising them when an annual test is required on their backflow assembly."
Enforcement follows the same path. If Phoenix moves to shut off water, it "will give ten days' written notice to the service address to be terminated before termination of water service" (City Code 37-146). That's the building. If the tenant holds the account and the lease says the landlord handles testing, the landlord may never see the reminder. Flip it around at a strip center where the landlord holds one account for the whole site, and the tenants never see anything until the water goes off.
Here's the kicker. A shutoff doesn't care what the lease says. Phoenix can terminate water if the customer "Fails to properly locate, install, test or maintain a required backflow prevention assembly" or "Fails to timely submit records of tests and repairs of a backflow prevention assembly." It can also impose a "civil penalty of not more than 1,000 percent per billing period on the charges for all water used" until the problem is fixed (City Code 37-146). The tenant loses water either way. The lease only decides who reimburses whom afterward.
The paperwork itself shows that both sides are in the picture. Phoenix's test report instructions ask the tester to "Provide management company name, address including zip code, contact person, and telephone number" and to "Provide the name of the owner and address, or owner's representative's address including zip, contact person and telephone number" (TRT 00335). Make sure your tester fills in the right people, so the city can reach whoever actually handles the test. For the full routing by city, see where to send backflow test reports in the Phoenix area.
How commercial leases usually split it
This part is general commercial leasing practice, not something the city codes spell out, and it isn't legal advice. Your actual lease language controls.
Triple-net (NNN) leases generally pass maintenance of the building systems that serve the tenant's space to the tenant, along with taxes and insurance. In a single-tenant NNN building where the tenant holds the water account, the yearly backflow test usually falls to the tenant as routine maintenance.
Gross or full-service leases generally keep building maintenance with the landlord, paid out of the rent. In that setup the landlord usually books and pays for the test.
Modified gross and multi-tenant leases often split it. At a shopping center, the assembly at the main service protects the whole property, so the landlord commonly handles it and may pass a share of the cost back through common area maintenance (CAM) charges. Phoenix and Scottsdale both list shopping centers or multi-tenant buildings on one service among the uses that need a reduced pressure (RP) assembly, so this setup is common.
Point-of-use devices are different. A soda machine, dental chair or chemical dispenser that a tenant brings in usually comes with its own backflow device, and many leases treat that as the tenant's equipment. Those still need testing when they're testable assemblies. See whether a soda or ice machine needs a backflow preventer for that side. A dental office also has an amalgam separator on the drain side, with its own records; see whether a dental office needs an amalgam separator.
### Common setups and who usually handles the test
| Setup | Who the city usually hears from | Who the lease often assigns (check yours) |
|---|---|---|
| Single-tenant building, NNN, tenant holds the water account | Tenant | Tenant |
| Single-tenant building, gross lease, landlord holds the account | Landlord | Landlord |
| Strip center, one service and one RP for all tenants | Landlord or property manager | Landlord, often recovered through CAM |
| Tenant's own point-of-use device (soda, dental, chemical) | Whoever holds the account | Tenant, as the tenant's equipment |
| Separate irrigation meter in the owner's name | Owner | Landlord, often through CAM |
| Fire line assembly | Owner or account holder, plus the Fire Marshal | Varies; testing needs a fire-permitted tester |
That last row has its own rules. In Phoenix, for fire lines "the initial and annual test must be performed by a certified tester who is also permitted by the City Fire Marshal to test fire lines or fire sprinkler systems" (City Code 37-143). Whoever pays, the test itself goes to a fire-licensed contractor.
What to put in the lease, and what to do now
Leases often mention "plumbing" and stop there. Backflow testing is a yearly legal deadline with a report attached, so it deserves its own lines. Before you sign, or at renewal, get these in writing:
- 1Who is the customer of record. Whose name is on the water account for each meter, including any irrigation meter.
- 2Who books the yearly test and by what date, with a buffer before the city's deadline.
- 3Who pays for the test, and separately who pays for repairs or a full replacement when an assembly fails. Those can be different parties.
- 4Who gets the notices. If the account holder isn't the party doing the test, require the account holder to forward city notices within a set number of days.
- 5Who keeps the records. Phoenix wants three years of records. Pick one party to hold them and share copies.
- 6Access. The tester needs to reach the assembly, and many are in locked cages. Say who holds the keys.
- 7Changes of tenant. Scottsdale asks customers to "notify the City of any change in mailing address, occupancy, or ownership within fifteen (15) days after such change occurs" (Revised Code 49-22). Build that into move-in and move-out.
If you already have a lease that says nothing about backflow, don't wait for a dispute. Find out who holds the account, find the assembly (our guide on where your backflow preventer is helps), and check when it was last tested. Then agree in writing, even by email, who handles this year's test. If the lease is unclear or you disagree about a large repair, have a commercial real estate attorney review it before anyone pays.
Already late? Read what happens if you miss your Phoenix backflow test deadline. If the test failed, what to do after a failed backflow test walks through the repair and retest. And for what the yearly test involves, see commercial backflow testing requirements in Arizona.
HQ Plumbing & Air tests, repairs and replaces backflow assemblies on commercial domestic water and irrigation lines, with upfront pricing and free estimates.