A cross-connection survey is the water provider's inspection of your property to find hazards and decide what backflow protection you need. A backflow test is the yearly gauge check a certified tester runs on an assembly you already have. The survey decides whether you need an assembly; the test proves it works.
What a cross-connection survey is, and who does it
Arizona's backflow rule, R18-4-215, makes each public water system responsible for protecting its mains. It says a system does that "by requiring the installation and periodic testing of backflow-prevention assemblies." To know where assemblies are required, the system first has to look. That look is the survey. (For what counts as a cross-connection in the first place, see what is a cross-connection.)
The cities write the right to look into their codes:
- Phoenix: the Planning and Development Director decides whether a facility is on the city's list of uses that need protection. Phoenix City Code 37-143 adds: "This responsibility includes inspection as necessary of all existing facilities connected to the City water system."
- Mesa: Mesa's code says "The Department may conduct inspections to determine whether any cross-connections or other public water system hazards exist and to determine compliance with this Chapter" (City Code 8-1-7).
- Scottsdale: an inspection is done to find cross-connections or other hazards, and Scottsdale's code says "The user's water system shall be available at all times during normal business hours for inspection by authorized personnel of the Water Resources Division" (Revised Code 49-65).
- Tempe: Tempe's code says "The user's system must be open for inspection at all reasonable times, and in all emergencies" (City Code 33-108).
The people who run these programs have their own credential. Arizona's backflow rule, R18-4-215, requires the person directly responsible for a backflow program at a system serving more than 50,000 people to be licensed as a "cross-connection control program specialist." That's a different credential from the one a tester holds.
The EPA's Cross-Connection Control Manual sets the bar for the survey itself: "The surveys should be conducted by personnel experienced in commercial and industrial processes." The EPA manual adds that a water department without experienced staff can have a consulting firm do the survey for it.
What the surveyor actually looks at
A survey is mostly walking and asking questions. The EPA's Cross-Connection Control Manual lays out a typical route. The surveyor starts where the water comes in, which it describes as "the potable entrance supply (the water meter in most cases)," then moves inside if the program calls for it.
They ask what the water is used for. The EPA manual's sample questions include "do the boilers have chemical additives?", whether cooling towers use chemical additives, and whether the site has a second water source, such as a well. They may ask for as-built drawings of the water piping.
Then they check the outlets. The EPA manual's list covers hose bibbs, slop sinks, washrooms, cafeterias and kitchens, fire protection and Siamese outlets, irrigation outlets, boiler rooms, mechanical rooms, laundries and the production floor.
### How they rate the hazard
The survey ends in a judgment about how bad a backflow event could be. Scottsdale's code spells out the four hazard factors it weighs: health, plumbing, nonhealth and system (Revised Code 49-60). A health hazard is one that could make people sick. A nonhealth hazard is one that is objectionable but not toxic. Mesa rates health, non-health and plumbing hazards the same way (City Code 8-1-4).
That rating picks the device. A health hazard usually means an air gap or an RPZ. A lower hazard may allow a double check. For how those two assemblies differ, see RPZ vs double check backflow preventers.
There are two depths of survey. The EPA manual calls the shallow one "containment": the surveyor spends only enough time to rate the whole facility and pick one assembly for the service line near the meter. The deep one goes to every fixture and outlet inside. Phoenix splits the two jobs: its plumbing code handles primary protection inside the building, and City Code Chapter 37 adds secondary protection for the city main (TRT 00635). Mesa's code reaches inside too, with point-of-use protection required at listed equipment (City Code 8-1-9).
What a backflow test is, and who does it
A test is narrower and more routine. A certified tester closes the downstream shutoff, hooks a differential pressure gauge to the test cocks, and checks that each check valve holds and, on an RPZ, that the relief valve opens when it should. It checks the device, not the building.
Arizona's backflow rule, R18-4-215, says each required assembly "shall be tested at least annually, or more frequently if directed by the public water system or the Department." It also says "Each assembly shall also be tested after installation, relocation, or repair." The tester must hold a current "general" tester certificate from an approved body, and most Valley providers also keep their own list of recognized testers. Who can test backflow assemblies in Arizona covers that in detail.
The owner pays for it and sends in the report. Mesa's code says the testing and servicing of each assembly "shall be performed at the expense of the customer" (City Code 8-1-11).
Tempe blends the two a little. Tempe's code asks the user to notify the city 15 days before an annual test, "so that an official representative of the department may witness the tests if so desired" (City Code 33-107).
### Survey vs test at a glance
Side by side, the two differ in purpose, timing and who shows up.
| Cross-connection survey | Backflow test | |
|---|---|---|
| Question it answers | What protection does this property need? | Does this assembly still work? |
| Who does it | Water provider staff or its agent | Certified backflow tester the owner hires |
| What gets checked | Water uses, outlets, equipment, piping, hazard level | Check valves, relief valve, shutoffs on one assembly |
| When | Plan review, city inspection, or a change in use | At least yearly, plus after install, move or repair |
| Result | Written findings: assembly required or not, and which type | Pass or fail report sent to the water provider |
| If it goes badly | Install the required assembly by a deadline | Repair or replace, then retest |
What happens after a survey
A survey that finds a problem starts a clock. The deadlines depend on the city.
Mesa gives a customer 60 calendar days after the notice of inspection results to correct deficiencies, and water service may be suspended based on the degree of hazard (City Code 8-1-7). Adding or removing a piece of equipment that could be a hazard "shall require a new inspection by the Department within 30 calendar days of such addition or removal."
Scottsdale sends a notice with 30 days to fix the problem. If it isn't fixed, a second notice by certified mail gives 10 more days before the supply line is disconnected (Revised Code 49-66). Scottsdale can also disconnect a user who refuses entry to its inspectors.
Phoenix gives an owner of an existing service three paths when it is referred for review (TRT 00635). The owner can get a permit and install the assembly near the meter. The owner can submit an alternative compliance plan. Or the owner can ask the city to review the internal plumbing and show it already complies. The last two require a plan review fee.
Refusing the survey doesn't get you out of it. Arizona's backflow rule, R18-4-215, requires an assembly where there is a real chance of a cross-connection problem and "entry to the premises is restricted to the extent that cross-connection inspections cannot be made with sufficient frequency or on sufficiently short notice." Mesa's code says the same thing in its own words (City Code 8-1-3).
Once the new assembly is in, the test cycle begins. Its first test comes right after installation, then every year after that.
### Two Valley scenarios
A Mesa cafe adds a soda machine. The new equipment triggers a new inspection within 30 days. If the inspector finds the carbonator needs an RPZ, the owner has 60 days to install it, and then a certified tester tests it and sends the report. For the equipment side, see whether a soda or ice machine needs a backflow preventer.
A Scottsdale property with a clean test history. Its double check has passed every annual test. Then a survey finds a new chemical feed on a boiler. The double check still works, but it's the wrong device for a health hazard. Passing tests didn't settle what the survey found.
### What to do now
Three habits keep both sides in order.
- 1Keep your test schedule. Testing is the part you control every year. Missing it has its own consequences; see missed backflow test deadline in Phoenix.
- 2Tell the provider about changes. New equipment, a new tenant or a change of use can mean a new review. New tenant or change of use walks through when that happens.
- 3Be ready for the visit. Have piping drawings on hand, know what each piece of water-using equipment does, and let the inspector in during business hours.
HQ Plumbing & Air tests, repairs and replaces backflow assemblies on domestic water and irrigation lines, with free estimates and upfront pricing.
For a medical or dental example, see whether a dental office needs a backflow preventer.