Backflow Tester Exam Questions & Answers 2026 (1–10)

Question 1

Which component in a Reduced Pressure Zone (RPZ) assembly maintains a differential pressure zone between the two check valves?

TheoryPractice · Accepted Answer

Relief valve. The relief valve in an RPZ assembly vents to atmosphere whenever the differential pressure between the two check valves drops below 2 psi, maintaining a reduced pressure zone. This is the defining characteristic of the RPZ assembly.

Question 2

How many independently acting check valves does a standard Reduced Pressure Zone (RPZ) assembly contain?

TheoryPractice · Accepted Answer

Two. An RPZ assembly contains two independently acting, spring-loaded check valves in series. The space between them is the reduced pressure zone monitored by the relief valve.

Question 3

What type of shutoff valves are typically required on either side of a testable backflow preventer assembly?

TheoryPractice · Accepted Answer

Full-port ball valves or resilient-seated gate valves. Full-port ball valves or resilient-seated gate valves are required as shutoff valves flanking testable backflow preventers because they allow full, unobstructed flow and can be fully closed for isolation and testing.

Question 4

A Double Check Valve Assembly (DCVA) consists of two check valves, two shutoff valves, and which additional feature that distinguishes it from a simple dual-check?

TheoryPractice · Accepted Answer

Test cocks between and outside the checks. A DCVA includes test cocks (typically four) that allow field testing of each check valve independently, unlike a simple dual-check that has no test ports. This testability is required for cross-connection control programs.

Question 5

A Pressure Vacuum Breaker (PVB) assembly must be installed at what minimum height above the highest downstream outlet or usage point?

TheoryPractice · Accepted Answer

6 inches. A PVB must be installed at least 6 inches above the highest downstream outlet or point of use to prevent the downstream system from submerging the air inlet valve, which could allow back-siphonage contamination.

Question 6

Which of the following hazard types can a Pressure Vacuum Breaker (PVB) protect against?

TheoryPractice · Accepted Answer

Back-siphonage only. A PVB protects only against back-siphonage. Because it opens to atmosphere under negative pressure, it cannot seal against backpressure conditions; for backpressure hazards an RPZ or DCVA must be used.

Question 7

An Atmospheric Vacuum Breaker (AVB) must NOT be installed where it may be subjected to continuous pressure for more than how many hours?

TheoryPractice · Accepted Answer

12 hours. An AVB is rated for intermittent service only and must not remain under continuous supply pressure for more than 12 hours, because the float/poppet seal can deform and fail, losing backflow protection.

Question 8

Where must an Atmospheric Vacuum Breaker (AVB) be located relative to any downstream shutoff valve?

TheoryPractice · Accepted Answer

Upstream of all downstream shutoff valves. An AVB must be upstream of all downstream shutoff valves. If a shutoff valve is downstream of the AVB and is closed, pressure can be trapped and held against the AVB, defeating its operation.

Question 9

During an RPZ field test, the differential pressure across the first check valve (check #1) must be at least how many psid to pass?

TheoryPractice · Accepted Answer

1.0 psid. The first check valve of an RPZ must maintain a differential pressure of at least 1.0 psid when tested. The relief valve must open at 2.0 psid below the supply pressure, but the check itself is evaluated at the 1.0 psid threshold.

Question 10

When testing an RPZ assembly, the relief valve must open at a differential pressure no less than:

TheoryPractice · Accepted Answer

2.0 psid below the supply pressure. The RPZ relief valve must open when the differential pressure between the zone and supply falls to at least 2.0 psid. If it opens at less than 2.0 psid the zone may not be adequately protected; if it never opens the device fails.

Backflow Tester Exam Questions & Answers 2026 (1–10)

More Backflow Tester practice questions

Free practice here. Timed mocks when you are ready.