TheoryBackflow Tester
Practice Test
700+ practice questions with detailed explanations. Pass your Backflow exam on the first try!
Heads up: the app and the web exam use separate accounts — a web unlock and an in-app purchase do not carry over. Buy on the web to practice on the web.
Backflow Tester exam — full Q&A walkthrough
Every question read aloud with the answer explained. Play it on your commute, then test yourself.
30 free Backflow Tester questions
Sampled across every topic area — not just the first page. Try them as a quiz or flip them as flashcards.
-
Assembly Types
Which component in a Reduced Pressure Zone (RPZ) assembly maintains a differential pressure zone between the two check valves?
Correct — A. 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. -
Assembly Types
How many independently acting check valves does a standard Reduced Pressure Zone (RPZ) assembly contain?
Correct — C. 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. -
Assembly Types
What type of shutoff valves are typically required on either side of a testable backflow preventer assembly?
Correct — B. 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. -
Assembly Types
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?
Correct — D. 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. -
Assembly Types
A Pressure Vacuum Breaker (PVB) assembly must be installed at what minimum height above the highest downstream outlet or usage point?
Correct — A. 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. -
Assembly Types
Which of the following hazard types can a Pressure Vacuum Breaker (PVB) protect against?
Correct — B. 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. -
Assembly Types
An Atmospheric Vacuum Breaker (AVB) must NOT be installed where it may be subjected to continuous pressure for more than how many hours?
Correct — C. 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. -
Assembly Types
Where must an Atmospheric Vacuum Breaker (AVB) be located relative to any downstream shutoff valve?
Correct — D. 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. -
Assembly Types
During an RPZ field test, the differential pressure across the first check valve (check #1) must be at least how many psid to pass?
Correct — A. 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. -
Assembly Types
When testing an RPZ assembly, the relief valve must open at a differential pressure no less than:
Correct — B. 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. -
Assembly Types
During RPZ testing, if the No. 2 check valve is found to be 'closed tight', the tester should record it as:
Correct — C. A 'closed tight' No. 2 check valve reading (needle does not move) is recorded as a pass because the check is holding and not allowing reverse flow; tight closure is acceptable and desirable. -
Assembly Types
During an RPZ test, you needle the No. 1 check and observe the differential gauge drop to 1.8 psid at which point the relief valve opens. What is the correct test result interpretation?
Correct — D. The RPZ relief valve is supposed to open at 2.0 psid below supply. If the gauge shows 1.8 psid when the relief cracks open, check #1 is not maintaining the required 2.0 psid differential. The first check fails its minimum differential requirement. -
Assembly Types
The minimum differential pressure at which either check valve of a Double Check Valve Assembly (DCVA) must hold to pass a field test is:
Correct — A. Both check valves in a DCVA must maintain a differential pressure of at least 1.0 psid during field testing. This threshold confirms the spring-loaded check is seating properly and providing measurable resistance. -
Assembly Types
When testing a DCVA, if check valve No. 2 reads 'closed tight' with no gauge movement, the correct interpretation is:
Correct — B. A 'closed tight' reading on DCVA check No. 2 indicates the check is fully seating and holding the pressure differential without any leak. This is an acceptable passing condition for the second check valve. -
Assembly Types
A DCVA is installed on a fire sprinkler service. During testing, check No. 1 reads 0.8 psid before the gauge stabilizes. What is the proper action?
Correct — C. A reading below the 1.0 psid minimum is a failing result. The tester records the fail and notifies the AHJ; unauthorized on-the-spot repair (especially on a fire sprinkler service) may violate procedures and require AHJ approval before the system is returned to service. -
Assembly Types
During a PVB field test, the air inlet valve must open at a supply pressure no greater than:
Correct — D. The air inlet (poppet) on a PVB must open at 1.0 psid or less as supply pressure is bled down. If the inlet does not open by the time differential drops to 1.0 psi the assembly fails because it would not protect under mild vacuum conditions. -
Assembly Types
The check valve inside a PVB assembly must hold a minimum differential of:
Correct — A. The internal check valve of a PVB must maintain at least 1.0 psid during the field test, confirming it seats properly and provides the primary barrier against reverse flow under normal operating pressure. -
Assembly Types
While testing a PVB, you open test cock No. 2 slowly and the air inlet immediately cracks open before you even begin to lower supply pressure. What does this indicate?
Correct — B. If the air inlet opens immediately upon cracking test cock No. 2, the check valve downstream of the air inlet is probably fouled or leaking, allowing a pressure drop that mimics back-siphonage. This points to a failing check valve. -
Assembly Types
A Spill-Resistant Pressure Vacuum Breaker (SRPVB) differs from a standard PVB primarily because it:
Correct — C. An SRPVB incorporates a sealed, spring-loaded poppet inside a pressurized body so that minor pressure fluctuations do not cause the air inlet to spill water. It still protects only against back-siphonage, not backpressure. -
Assembly Types
Can a Spill-Resistant PVB (SRPVB) be installed where backpressure conditions may exist?
Correct — D. Despite its sealed body, an SRPVB is approved only for back-siphonage conditions. Under true backpressure the internal poppet can be forced open from downstream, allowing contamination to enter the supply. An RPZ or DCVA is required for backpressure hazards. -
Assembly Types
Which assembly is the ONLY one approved for use against high-hazard backpressure AND back-siphonage conditions?
Correct — A. The RPZ assembly is the highest level of mechanical backflow protection and is the only testable assembly approved for both high-hazard backpressure and back-siphonage. Its relief valve provides a visible fail-safe even if both checks fail. -
Assembly Types
A DCVA is typically approved for which hazard classification?
Correct — B. A DCVA provides protection for low-to-moderate (non-health) hazard scenarios involving both backpressure and back-siphonage. It is not approved for high-hazard (toxic/health) situations because it lacks the fail-safe relief valve of an RPZ. -
Assembly Types
A landscape irrigation system uses a pump that can develop pressure exceeding supply pressure. Which assembly is most appropriate?
Correct — C. When a pump can develop pressure exceeding supply pressure, a backpressure condition exists. Only an RPZ (or in some jurisdictions a DCVA for low-hazard) can protect against backpressure; PVBs and AVBs cannot. -
Assembly Types
A hospital's oncology lab requires backflow protection on its dedicated water supply. Which assembly is required by most cross-connection control regulations?
Correct — D. Hospitals—and oncology labs in particular—are classified as high-hazard due to the risk of toxic or pathogenic contamination. An RPZ is required because it provides the highest level of mechanical protection and its relief valve provides an audible/visible alert if protection is compromised. -
Assembly Types
What is the minimum clearance typically required below the relief valve port of an RPZ assembly to the floor or drain?
Correct — A. Most codes require at least 12 inches of clearance beneath the RPZ relief valve to allow for unrestricted discharge during a backflow event or test, and to prevent the drain from flooding back into the relief port. -
Assembly Types
An RPZ assembly installed in a vault must have the relief valve discharge:
Correct — B. In a vault, the relief valve discharge must drain to a sump with an indirect connection (air gap) to the drain to prevent the relief valve from being submerged. A submerged relief port would back up and defeat the RPZ's fail-safe function. -
Assembly Types
Why is an RPZ assembly NOT permitted to be installed below grade in a vault in many jurisdictions?
Correct — C. If a vault floods and the water level rises above the relief valve port, the RPZ's primary fail-safe (atmospheric discharge) is negated. Contaminated water can be drawn back through the open relief valve into the potable supply, which is why many jurisdictions prohibit below-grade RPZ installations. -
Assembly Types
A DCVA is being installed for a commercial fire sprinkler system. The assembly must be installed so that flow is:
Correct — D. All backflow prevention assemblies are directional; flow must be from the supply (inlet) to the protected system (outlet) as marked by the arrow on the assembly body. Reversing the assembly defeats both checks and the test cock ports. -
Assembly Types
What type of spring force keeps the check valves in an RPZ or DCVA in the CLOSED position under normal static conditions?
Correct — A. Backflow preventer check valves use calibrated compression (coil) springs to maintain the disc against its seat when forward flow stops. This ensures the check closes immediately when flow reverses, without relying on gravity or system pressure. -
Assembly Types
If a check valve disc is fouled with debris and cannot seat fully, what condition results?
Correct — B. Debris lodged between the disc and seat prevents full closure, creating a leakage path. Reverse flow can then travel past the check valve, which is the primary failure mode for check valves and why testable assemblies are required in cross-connection control programs.
Backflow Tester sample questions
Tap any question below to reveal the answer and a plain-English explanation.
Assembly Types During testing, the technician slowly opens test cock No. 3 of an RPZ and the differential gauge reads 2.8 psid, then slowly bleeds down to 2.0 psid at which point the relief valve opens and the gauge cannot be driven lower. What is the correct conclusion?
A. Fail — relief opened below 3.0 psid minimum
B. Fail — check #1 did not hold 5.0 psid
C. Pass — relief opened at 2.0 psid (≥ 2.0 psid) and check #1 held above 1.0 psid ✓
D. Inconclusive — gauge fluctuation means test must be repeated
Correct — C. The RPZ passes when (a) check #1 holds ≥ 1.0 psid differential, and (b) the relief valve opens at ≥ 2.0 psid below supply pressure. Both conditions are met here: check #1 held above 1.0 psid before relief opened, and relief opened exactly at 2.0 psid, which meets the minimum.
Cross-Connection Control What is a cross-connection in a potable water system?
A. A pipe fitting that joins two different pipe sizes
B. A valve that connects two separate water mains
C. Any actual or potential link between a potable water supply and a source of contamination ✓
D. A meter installed to measure flow between two service lines
Correct — C. A cross-connection is any physical link or arrangement between a potable water supply and any other system containing non-potable water, chemicals, or other substances. It creates a pathway for contamination to enter the drinking water supply.
Field Testing Before beginning a field test on a double check valve assembly (DCVA), what must the tester do first?
A. Notify the water purveyor or their designee ✓
B. Close the downstream shut-off valve only
C. Flush the test cocks open for 10 minutes
D. Remove the check valve springs for inspection
Correct — A. The water purveyor must be notified before any field test begins so that service interruptions and water quality issues can be managed. This is a regulatory requirement in most jurisdictions.
Hydraulics & Theory What is the standard unit of pressure used in plumbing and backflow prevention in the United States?
A. Pascals (Pa)
B. Pounds per square inch (psi) ✓
C. Bar
D. Atmospheres (atm)
Correct — B. In U.S. plumbing and backflow prevention, pressure is expressed in pounds per square inch (psi). While other units exist internationally, psi is the standard for domestic codes and equipment ratings.
Regulations & Codes Which federal agency establishes the primary drinking water standards that drive backflow prevention requirements in the United States?
A. Environmental Protection Agency (EPA) ✓
B. Occupational Safety and Health Administration (OSHA)
C. Department of Housing and Urban Development (HUD)
D. Federal Emergency Management Agency (FEMA)
Correct — A. The EPA establishes primary and secondary drinking water standards under the Safe Drinking Water Act (SDWA), which are the foundation for cross-connection control and backflow prevention programs nationwide.
Troubleshooting & Repair What is the primary purpose of test cocks on a backflow preventer?
A. To allow testers to measure differential pressure across check valves ✓
B. To drain the assembly for winterization
C. To flush debris from the system
D. To regulate incoming water pressure
Correct — A. Test cocks provide access points for differential pressure gauges so testers can measure pressure across each check valve and the relief valve. They are not designed for draining, flushing, or pressure regulation.
Safety OSHA classifies soil into four categories for excavation safety purposes. Which classification represents the least stable soil requiring the most stringent protective measures?
A. Type A — very stable cohesive soil with no fissures
B. Stable rock — does not require a protective system
C. Type B — moderately stable, some cracking
D. Type C — granular, fissured, subject to vibration or water seepage ✓
Correct — D. Type C is the least stable OSHA soil classification. It includes granular soils (gravel, sand), fissured cohesive soils, soils subject to water seepage, and previously disturbed soils. Type C requires the most conservative protective measures, such as a maximum 1½H:1V slope ratio.
Test Procedures Before attaching a differential pressure gauge to a double check valve assembly, the tester should first:
A. Close the downstream shutoff valve to isolate the assembly ✓
B. Open the test cocks fully to flush debris
C. Record the static line pressure
D. Verify the date on the gauge calibration sticker
Correct — A. The downstream shutoff valve must be closed first to stop flow through the assembly so that meaningful pressure readings can be obtained during testing. Testing under flowing conditions produces inaccurate results.
About the Backflow Tester test
Pass your Backflow Exam with confidence. Backflow Tester Exam Prep gives you 700+ realistic practice questions with clear, detailed explanations for every answer.
Covers every topic
Cross-Connection Control, Hydraulics & Theory, Assembly Types, Test Procedures, Troubleshooting & Repair, Regulations & Codes — and more.
WHY Backflow PREP
- 700+ exam-style questions, written and reviewed for accuracy
- A detailed explanation for every answer — understand WHY
- Realistic mock exams that mirror the real test
- Track your accuracy by subject with smart analytics
- A personalized study plan that keeps you on pace
Whether it's your first attempt or a retake, our questions and explanations help you master the material and pass on your first try.
You will be tested on
- Core formulas and field calculations
- Codes, standards and compliance
- Safe work practices and PPE
- Tools, materials and on-site reference
How TheoryPractice helps you pass
- Real exam-style questions with instant, detailed explanations
- Full timed mock exams that mirror the real test format
- Flashcards & quiz modes from the same question bank
- Progress tracking so you know exactly when you're ready
Topics in this question bank
Core formulas and field calculations
Codes, standards and compliance
Safe work practices and PPE
Tools, materials and on-site reference
Full Backflow Tester bank + unlimited mocks
Try 30 questions free. Unlock the complete Backflow Tester question bank, every explanation, and unlimited timed mock exams. Practice on any device.
Unlock Backflow Tester →