Inside a Backflow Test: What the Technician Actually Does

If you’ve scheduled an annual test and you’re picturing someone “checking a valve,” you’re not wrong—but there’s a lot more precision involved than most people expect. A certified tester isn’t guessing or eyeballing your backflow preventer.

They’re performing a documented, gauge-based procedure to confirm the assembly is protecting your drinking water from contamination and backpressure/back-siphonage events.

This guide explains, in plain language, what exactly the technician will be doing to the device during the test, what you may notice at the faucets or irrigation system, and what’s normal. It’s based on what our Backflow Testing Long Beach experts recommend for homeowners, HOAs, commercial sites, and multi-tenant properties served by Atlas Backflow Services.

First, What “Backflow Testing” Means (In One Minute)

A backflow prevention assembly contains internal components—typically check valves, shutoff valves, and (depending on type) a relief valve or air inlet—designed to keep non-potable water from flowing backward into the potable supply.

During a test, the technician verifies that those internal parts hold pressure and seal properly under specific conditions.

Our Backflow Testing Long Beach experts recommend thinking of it like a calibrated “health check” with measurable pass/fail criteria—not a casual inspection.

Step 1: Identify the Assembly and Confirm Access

When the technician arrives, they’ll locate the backflow assembly and confirm:

• Assembly type (commonly RP/RPZ, Double Check (DC/DA), PVB, or SVB)

• Size, manufacturer, and model (important for correct procedure and reporting)

• Serial number (often required for the test report)

• Site conditions (clearance, drainage, enclosure condition, leaks, corrosion)

Our Backflow Testing Long Beach experts recommend ensuring gates are unlocked and the unit is accessible before the appointment—especially if it’s behind landscaping, in a cage, or in a tight mechanical area.

Step 2: Perform a Visual Pre-Check (Before Touching Test

Cocks)

Before gauges come out, the technician typically checks for issues that could affect safety or results, such as:

• Existing leaks at fittings, test cocks, or relief ports

• Damaged shutoff handles or missing test cock caps

• Improper installation concerns (clearance, height, drainage)

• Signs the assembly may have been tampered with or impacted

This isn’t the official “test” yet—it’s the setup for a clean, accurate procedure. It’s also why our Backflow Testing Long Beach experts recommend notifying your tester if you’ve noticed dripping, water hammer, or recent plumbing work.

Step 3: Shut Down Water Flow in a Controlled Way

To test internal seals, the technician will manipulate the assembly’s shutoff valves in a specific order. Depending on the assembly type and site piping, this can cause:

• A brief interruption of water to irrigation, a building line, or a process line

• Temporary pressure changes (you may hear water movement in the pipe)

Our Backflow Testing Long Beach experts recommend planning the test during a low-impact window, especially for restaurants, medical offices, apartment buildings, or properties with irrigation timers.

Step 4: Connect Calibrated Test Gauges to the Test Cocks

Backflow assemblies include small ports called test cocks. The technician will:

1. Remove test cock caps (if present)

2. Verify the ports are serviceable

3. Attach a calibrated differential pressure gauge using hoses/fittings

4. Carefully bleed air from the gauge lines to stabilize readings

This is a critical part of the process. Our Backflow Testing Long Beach experts recommend using properly maintained and calibrated equipment because small measurement errors can cause incorrect pass/fail outcomes.

Step 5: Run the Actual Performance Test (Varies by Assembly Type)

The exact sequence depends on what you have installed. Here’s what the technician is doing internally, in practical terms:##### For a Double Check (DC/DA) Assembly The technician verifies that:

• Check valve #1 holds and maintains a minimum pressure differential

• Check valve #2 holds and maintains a minimum pressure differential

They do this by closing/opening valves in sequence and observing the gauge response. A “pass” indicates both checks are sealing and doing their job.##### For an RP (Reduced Pressure / RPZ) Assembly An RP includes two checks plus a relief valve. The technician typically verifies:

• Check #1 holds and meets performance criteria

• The relief valve opens at the correct point (not too early, not too late)

• Check #2 holds

Because the relief valve is designed to discharge under certain conditions, you may see brief water discharge during testing. That’s often normal.

Our Backflow Testing Long Beach experts recommend ensuring the area has proper drainage and that nothing sensitive (electrical, stored items) is directly below the discharge point.##### For a PVB (Pressure Vacuum Breaker) A PVB is common on irrigation. The technician confirms:

• The check valve is holding as required

• The air inlet opens appropriately when the supply pressure drops

This often involves controlled valve positioning and gauge observation to confirm the device breaks a vacuum as designed.

Step 6: Record Readings and Determine Pass/Fail

During the test, the technician records specific gauge readings and outcomes, typically including:

• Measured differentials across checks

• Relief valve opening point (for RP)

• Any irregular behavior (slow closing, unstable readings)

Then they determine whether the assembly passes or fails according to the applicable testing procedure for that model/type. Our Backflow Testing Long Beach experts recommend keeping these records organized year to year—especially for multi-site property portfolios.

Step 7: Restore the System and Verify Normal Operation

Once testing is complete, the technician will:

• Close test cocks and remove gauge equipment

• Return shutoff valves to their normal operating position

• Confirm the assembly is pressurized correctly

• Check for leaks created or revealed by valve cycling

• Replace test cock caps (if applicable)

In many cases, the technician will also advise if they noticed conditions that could lead to future failure (corrosion, worn shutoffs, persistent weeping).

What You Might Notice During the Test (And What’s Normal)

Our Backflow Testing Long Beach experts recommend expecting a few temporary effects:

• Brief water shutoff to irrigation or a line served by the assembly

• Momentary sputtering at nearby fixtures (air in the line)

• Short discharge from an RP relief port during certain steps

• Audible water movement as valves are repositioned

These are usually normal and temporary. If you see continuous discharge after the technician restores service, that’s worth flagging immediately.

If the Device Fails, What Happens Next?

A failed test doesn’t necessarily mean full replacement—many issues can be corrected by repair, cleaning, or rebuilding, depending on the assembly condition and local requirements.Typically, after a failure the technician will:

• Explain which component failed (check #1, check #2, relief valve, air inlet)

• Recommend next steps and options

• Coordinate repair/retest scheduling if needed

Our Backflow Testing Long Beach experts recommend addressing failures promptly—both to restore protection and to avoid compliance headaches.

Quick FAQ: Common Questions About the Testing Process

#### Will the technician disassemble the device during a standard test?

Usually, no. A standard test is performed through test cocks with gauges. Disassembly typically happens only during repair/rebuild.#### How long does a test take?

Many routine tests are relatively quick once access is clear, but time varies by assembly type, condition, and site complexity.#### Is water discharge from an RP backflow preventer during testing normal?

It can be. Our Backflow Testing Long Beach experts recommend providing drainage and keeping the discharge area clear.

Schedule Confident Backflow Testing in Long Beach

Knowing what happens during the test makes the appointment smoother — and helps you plan around any brief water interruptions.

At Atlas Backflow Services, we follow proper procedures, use calibrated equipment, and document results clearly — exactly what our Backflow Testing Long Beach experts recommend for reliable compliance and peace of mind.If you want, tell me what type of device you have (RP, DC, or PVB) and whether it serves irrigation or the building, and I’ll tailor a short “What to Expect” checklist you can add to your website’s booking page.