Backflow testing: what to know

What the job involves, what changes the price, and what to ask a pro.

What backflow testing is

Backflow testing checks the backflow preventer on an irrigation or domestic line with calibrated gauges, to confirm it blocks contaminated water from flowing back into the public supply. The tester records the results and the report is filed where the water provider or local rules require it.

Signs you need it

  • Your water provider or the local rules require an annual test, and a notice or a reminder has come in
  • You have an irrigation system with a backflow preventer, and the valves have been replaced or the system has been changed
  • A backflow assembly is leaking, dripping from the relief valve, or has a valve that does not hold
  • The assembly is above ground and has been damaged, frozen, or buried in landscaping
  • You are installing a new backflow assembly, and the first test is needed before the system is used

What the pro does

  • Identify the assembly type and its location, and confirm the shutoffs and the test cocks are accessible
  • Connect the calibrated test gauges to the test cocks, with the correct hoses and the bleed valves
  • Test the check valves and the relief valve for holding and opening pressure, using the gauge readings
  • Record the readings on the official test form, with the date, the tester's details and the assembly details
  • Repair or replace any valve that fails, and retest the assembly after the repair
  • File the report where the water provider or local rules require it, and give the customer a copy

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Type of assembly, since each type has a different test sequence and a different number of checks
  • Number of assemblies on the property, such as an irrigation line and a domestic line
  • Access to the assembly, including buried, hard-to-reach or landscaped locations
  • Whether a failed valve must be repaired or replaced before the report can be filed
  • Retest needed after a repair, which adds a second visit
  • Filing and reporting requirements set by the water provider or local rules

What a written quote should spell out

  • Assembly type, size and location, and the test sequence used
  • Test results for each check valve and the relief valve
  • Any repairs or replacements needed, with the parts named
  • Retest after repair, if included
  • Filing of the report, and the copy given to the customer

Questions to ask before you hire

  • Are you a certified tester for the assembly type, and do you have the calibrated gauges?
  • What are the test results for each valve, and what do they mean?
  • Which valve failed, and what does it take to fix it?
  • Who files the report, and how will I know it was filed?
  • Will you retest after any repair, and is that included?
  • When is the next test due, and who will remind me?

Red flags

  • Pro who signs a test report without running the test on the gauges
  • Pro who uses gauges that are not calibrated, or does not show the calibration
  • Pro who says the assembly passed without showing the readings
  • Pro who recommends a replacement without testing the assembly first

What you can do yourself

A homeowner can keep the assembly clear of landscaping and check that the test cocks are accessible. Do not test the assembly yourself unless you are a certified tester, and do not remove or change the assembly, since a wrong test or a bad repair can let contaminated water back into the supply.

Licenses and permits

Backflow testing is commonly done by certified backflow testers, and many areas require the tester and the plumber who repairs the assembly to be certified or licensed. Check with your state or local licensing agency and your water provider for the certification and filing rules.

Backflow testing questions

Why does a backflow preventer need to be tested?

The check valves and the relief valve wear, and a failed valve can let water flow backward. The test shows whether each valve still holds, which is the only way to know.

How often does a backflow assembly need testing?

It depends on the local rules and the assembly type. Your water provider can tell you the required interval, and the tester can confirm when the next test is due.

What happens if the assembly fails the test?

The valve is repaired or replaced and the assembly is retested. The report should show the pass before the assembly goes back into service, and your water provider can confirm what it accepts.

Can I test the assembly myself?

Only if you are a certified tester with the right gauges and the right form. Most homeowners need a certified tester to do the test and file the report.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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