Backflow 101 (and why testing exists)

Backflow is water moving the wrong way—back into the public system or your home’s potable supply. It happens in two main ways:

• Backpressure: Your system’s pressure becomes higher than the public side (for example, a booster pump or heated water expanding).

• Backsiphonage: Public pressure drops (think main break or hydrant use), and water is pulled backward from your lines.

To stop this, homes with risk factors have a backflow prevention assembly. For Boise homeowners, the most common devices are:

• PVB (Pressure Vacuum Breaker) – Common on lawn irrigation.

• DCVA/DC (Double Check Valve Assembly) – For low-to-moderate hazard uses.

• RP/RPZ (Reduced Pressure Principle Assembly) – For higher-hazard situations or where fertilizers/chemicals could be present.

Annual testing verifies that springs, check valves, and relief ports still function exactly as designed. These are wear parts exposed to Idaho’s seasonal swings—so yes, parts can stick, crack, or drift out of spec.

Where your device is (and how to spot it)

• Irrigation systems: Look for a brass assembly above grade, usually near the front or side yard. PVBs and RPs are easy to spot: test cocks, shutoff handles, and often a U-shaped relief opening.

• Boilers/radiant heat: You’ll see the device near the boiler, typically paired with a pressure-reducing valve and isolation valves.

• Accessory lines: Any connection feeding hose bib manifolds, hose reels, or auxiliary tanks may include a smaller backflow device.

If you’re not sure what you have, snap a photo and we’ll ID it over the phone before your appointment.

What the test includes (step by step)

A licensed backflow tester from A+ will:

• Verify the assembly type and location against your notice or prior records.

• Isolate the assembly using the upstream and downstream shutoff valves.

• Attach calibrated test equipment to the test cocks.

• Measure spring and check performance (relief valve opening point for an RP; check valve tightness for DCs; air-inlet function for PVBs).

• Record readings and condition (leaks, freeze damage, missing caps, etc.).

• Pass/fail determination and any onsite adjustments/repairs we can make immediately.

• Provide the compliance report and, if required by your provider, submit the results on your behalf.

The whole process is noninvasive and typically quick—unless we discover freeze damage or debris lodged in a check.

The “Pass the First Time” checklist

Do these the day before (or morning of) your appointment to avoid the most common failure points:

• Clear access. Trim shrubs and move landscaping rock or mulch away from buried shutoffs. We need room around the assembly.

• Check the shutoff handles. If a handle is broken or seized, note it—repairs may be needed before accurate testing is possible.

• Confirm water is on to the device. Irrigation controllers can leave valves closed; ensure the upstream valve is open so we can test.

• Open the enclosure. If your assembly is in a box or insulated cover, unlock or unstrap it.

• Turn the controller to “Off.” For sprinkler systems, prevent the zones from cycling during the test.

• Know where the main shutoff is. Rarely needed, but good to have ready if a downstream leak shows up during testing.

• Winterized? If the irrigation system is still blown out and dry, tell us—we’ll coordinate testing with spring start-up or provide a temporary setup to test correctly.

Why devices fail (and what we do about it)

1) Freeze damage
Boise’s fall and winter swings are hard on exposed assemblies. A single freeze can crack the bonnet or pop an internal spring.
Fix: Replace cracked bonnets or internals, re-test, and add an insulated cover. Consider relocating or adding heat tape if the spot is wind-prone.

2) Debris on checks
Sand or mineral flakes wedge in a check valve so it won’t seal.
Fix: Disassemble, clean seats and checks, reassemble with new O-rings if needed, re-test.

3) Worn springs and seals
Over time, springs lose tension and rubber parts harden.
Fix: Install a manufacturer repair kit matched to your model (springs, checks, seals), then verify performance.

4) Incorrect installation height or orientation
PVBs must be installed vertically and above downstream piping.
Fix: Correct the orientation/height and re-test. We’ll tell you if a different device type makes more sense for your system.

5) Leaking or seized isolation valves
If the shutoffs won’t close or are dripping, a valid test isn’t possible.
Fix: Repair/replace the shutoff(s), then complete the test.

We stock common repair kits and hardware so you’re not left waiting between “fail” and “pass.”

Scheduling tips that save you headaches

• Book before irrigation season. Early spring testing catches winter damage while parts are easy to source.

• Combine services. Pair backflow testing with sprinkler start-up and a water-heater flush—we’re already onsite, so you knock out multiple maintenance items at once.

• Keep records handy. If you’ve moved recently, ask for the previous test report. It helps us bring the right kit.

• Set a reminder. Put a recurring calendar event two weeks before your anniversary month to stay compliant.

What if my provider already sent a notice?

Great—forward it to us or attach a photo when you use the [Contact] form. We’ll:

• Confirm the device type and deadline

• Schedule testing

• Perform any necessary repairs

• File the test report with your provider (if required) and send you a copy for your records

If you’ve missed the window and received a shutoff warning, let us know in the message—we prioritize those calls.

Backflow and safety: when it’s more than paperwork

Most of the year, backflow is “out of sight, out of mind.” But the risk is real:

• Fertilizers/chemicals drawn back through irrigation lines during a pressure drop

• Heated loops (boilers, radiant) pushing water backward under backpressure

• Hose siphons when sprayers or tanks are connected without proper protection

If you suspect a contamination event—odd taste or odor after a main break, for example—treat it like a plumbing emergency and call us right away. We’ll isolate potential sources, flush lines, and advise on next steps.

FAQs

Do all Boise homes need annual testing?
Not every home. Testing is required when you have a qualifying backflow prevention assembly—most commonly on lawn irrigation. Your water provider’s notice will specify whether your address requires testing and the due date.

Is a hose vacuum breaker enough?
For standard hose bibs, an approved vacuum breaker is a good layer of protection. It’s not a substitute for a dedicated backflow assembly on an irrigation system that injects fertilizer/chemicals or has underground piping.

Can I move my device lower to hide it?
Some devices must be a certain height and orientation to work properly (and pass). We can review concealment options (enclosures/landscaping) while keeping your installation compliant.

Do I have to winterize an outdoor assembly?
Yes. Drain and protect exposed assemblies each fall to prevent freeze damage. If you’ve upgraded to a heat-pump water heater or done plumbing changes, re-check your isolation valves and drain points to ensure winterization still works as planned.

What happens after the test?
We give you a pass/fail report. If it passes, you’re done until next year. If it fails, we’ll quote repairs immediately and re-test after the fix—same visit when possible.

The A+ way: fast test, clean paperwork, zero guesswork

Here’s what you can expect when you schedule with A+ Drain Cleaning & Plumbing:

• Easy booking—send your notice through the Contact page or call.

• On-time arrival with the right test kit for your device.

• Clear communication—we show readings, explain results, and present repair options if needed.

• On-the-spot repairs for common failures to help you pass the same day.

• Filed documentation—we submit the test form to your provider (when required) and email you a copy.

Ready to get compliant (and stay that way)?

Knock out backflow testing now and relax for the rest of the year. If your assembly needs a little TLC, we’ll handle the repair and re-test so you pass. Use the Contact form to upload your notice and pick a convenient time, or call for same-day availability.