How to Read a Backflow Test Report and What the Numbers Mean
February 28, 2026
You got your annual backflow test done. The tester handed you a report with numbers like "#1 Check: 8.2 psi" and "RV Opening: 3.1 psi" and you nodded like you understood. But now you're staring at it wondering what any of it actually means.
You're not alone. Most property owners have never been taught how to read these reports. This guide translates the technical jargon into plain English so you can understand what your device is doing — and whether you should be concerned.
The Basics: What's Being Measured
A backflow test measures pressure differential — the difference in water pressure across each internal component of your backflow prevention device. This is measured in pounds per square inch (psi) using a specialized differential pressure gauge kit.
The core question the test answers: Is each component creating enough resistance to prevent water from flowing backward?
If a component creates sufficient pressure differential (resistance), it passes. If it doesn't, it fails — and that component needs repair or replacement.
Reading an RPZ Assembly Report
Reduced Pressure Zone (RPZ) assemblies are the most complex backflow devices, with three testable components. Here's what each reading means:
Check Valve #1 (First Check)
What it is: The first line of defense. This valve sits closest to the supply side (the street/utility side) and stops water from flowing backward.
What the number means: The pressure differential reading shows how much resistance this valve creates. A reading of 8.2 psi means there's 8.2 pounds per square inch of pressure difference across this valve — it's holding strong.
Minimum to pass: 5.0 psi (most jurisdictions)
Reading health guide:
- 10+ psi = Excellent — valve is in great shape
- 7-10 psi = Good — normal range for a healthy valve
- 5-7 psi = Acceptable — passes but worth monitoring
- Below 5 psi = Fails — needs repair
Check Valve #2 (Second Check)
What it is: The backup valve closest to your property's plumbing. It provides a second layer of protection.
Minimum to pass: 1.0 psi (most jurisdictions)
Reading health guide:
- 3+ psi = Excellent
- 2-3 psi = Good
- 1-2 psi = Acceptable — passes but monitor closely
- Below 1 psi = Fails — needs repair
Relief Valve (RV) Opening Point
What it is: The safety net unique to RPZ assemblies. If both check valves fail, the relief valve opens and dumps water out rather than allowing contamination into the supply.
What the number means: This reading shows the pressure differential at which the relief valve opens. Lower is better for this reading — you want the relief valve to open quickly if there's a problem.
Minimum to pass: The relief valve must open at a pressure differential less than the #1 check valve reading and typically at 2.0 psi or less below the #1 check reading.
Example: If your #1 check reads 8.2 psi, your relief valve should open somewhere below 8.2 psi — typically around 3-5 psi is normal.
Reading health guide:
- Opens at 2-4 psi = Normal and healthy
- Opens at 4-6 psi = Acceptable if below #1 check
- Opens above #1 check reading = Fails — relief valve is stuck or fouled
- Doesn't open = Fails — immediate repair needed
Reading a DCVA Report
Double Check Valve Assemblies (DCVA) are simpler — they have two check valves and no relief valve.
Check Valve #1
Minimum to pass: 1.0 psi
Reading health guide:
- 5+ psi = Excellent
- 3-5 psi = Good
- 1-3 psi = Acceptable
- Below 1 psi = Fails
Check Valve #2
Minimum to pass: 1.0 psi
Same scale as #1. Both valves need to hold at least 1.0 psi independently.
Reading a PVB Report
Pressure Vacuum Breakers (PVB) have two testable components:
Air Inlet Valve
What it is: A valve that opens to let air into the device when supply pressure drops, breaking the vacuum that could cause backflow.
Minimum to pass: Must open at 1.0 psi or greater above downstream pressure.
Check Valve
Minimum to pass: 1.0 psi
What "Barely Passing" Tells You
A device that reads 5.1 psi on a 5.0 psi minimum is technically passing — but it's telling you something. Internal components wear gradually, and a reading that barely clears the threshold today will likely fail next year.
If your readings are trending downward year over year, talk to your tester about whether a rebuild (replacing internal seals and components) makes sense. A rebuild typically costs $100-$300 and can restore your device to like-new readings, extending its useful life by 5-10 years.
Compare this year's report to last year's:
| Component | Last Year | This Year | Trend |
|---|---|---|---|
| #1 Check | 10.1 psi | 7.3 psi | ⚠️ Declining |
| #2 Check | 3.4 psi | 2.8 psi | Normal wear |
| Relief Valve | 3.0 psi | 3.2 psi | Stable |
In this example, the #1 check dropped nearly 3 psi in one year. It still passes, but at this rate, it may fail next year. Proactive repair now is cheaper than an emergency repair later.
Common Report Fields You Might See
Beyond the pressure readings, here are other fields on the report and what they mean:
"Test Gauge Serial #" — The serial number of the tester's differential pressure gauge. Required to verify the equipment was calibrated.
"Gauge Calibration Date" — When the test gauge was last calibrated. Most jurisdictions require annual calibration. If this date is more than a year old, the test results may not be accepted.
"Apparent Position of Shutoffs" — Whether the shutoff valves (gate valves or ball valves) on either side of the device are fully open and functional. These are needed for testing and for emergency shutoff.
"Leaked" or "Dripped" — Notes about whether a check valve showed visible leaking during the test. A small drip may not cause a numerical failure but indicates wear.
"Repairs Made" — If the tester repaired the device during the visit, this section documents what was replaced. Common repairs include rubber disc assemblies, seat inserts, springs, and o-rings.
"Retest Results" — If repairs were made, the retest readings should show improvement. Your utility needs to see passing retest numbers.
Red Flags on Your Report
Watch for these warning signs:
- Any reading below the minimum threshold — Device failed and needs repair
- Dramatic year-over-year decline — Even if still passing, indicates accelerating wear
- Multiple components near threshold — Entire device may need a rebuild
- Missing or expired gauge calibration — Test may not be accepted by utility
- Notes about external damage — Corrosion, physical damage, or freeze damage noted by tester
What to Do With Your Report
- Keep a copy — Store it with your property records
- Compare to last year — Look for declining trends
- Follow up on failures — Make sure repairs and retests are completed before your deadline
- Verify submission — Confirm your utility received the report
- Ask questions — Your tester should be willing to explain the results
The Bottom Line
Your backflow test report isn't just bureaucratic paperwork — it's a diagnostic snapshot of a device that protects your drinking water. Understanding the numbers helps you plan ahead, catch problems early, and make informed decisions about maintenance and replacement.
For a broader overview of the testing process, read what happens after you get a backflow test notice. If you need to find a tester for your next annual test, browse certified testers by state.
Sources
This article references guidance and regulations from authoritative sources including:
- USC Foundation for Cross-Connection Control and Hydraulic Research - Manual of Cross-Connection Control — Standard test procedures and pass/fail thresholds for backflow prevention assemblies
- American Water Works Association (AWWA) - Manual M14: Backflow Prevention and Cross-Connection Control — Technical reference for device testing standards
- American Society of Sanitary Engineering (ASSE) - Standard 5110: Backflow Prevention Assembly Tester — Equipment calibration and test procedure requirements
- U.S. Environmental Protection Agency (EPA) - Safe Drinking Water Act — Federal framework for drinking water protection programs
Last updated: February 28, 2026