What Is Backflow Testing?

Backflow is water flowing the wrong way in a plumbing system. Normally, clean water flows from the city main into your property. Under the wrong conditions, water from inside your property can flow back out into the main.

It happens two ways. Back-siphonage is when pressure in the main drops, for example during a water main break or when firefighters open hydrants, and water gets pulled backward. Backpressure is when something on your side, like a pump or a boiler, pushes water at a higher pressure than the supply.

The danger is the cross-connection: any place where your drinking water piping meets something you would never want to drink. Lawn irrigation, pools, boilers, fire sprinkler lines, and some commercial equipment are common examples.

A backflow prevention assembly is a set of valves installed where your water line meets the cross-connection. It lets water flow in and blocks it from flowing back out.

Inside are check valves held shut by springs, and on some assemblies a relief valve that opens to dump water if something goes wrong. Springs weaken and rubber seals wear or collect debris, so an assembly that worked perfectly when it was installed can quietly stop working years later. That is why it has to be tested.

If your property has a testable backflow assembly, you almost certainly need an annual test. That usually includes:

• Homes with lawn sprinkler systems or pools.
• Restaurants, churches, offices, retail buildings, and apartment complexes.
• Buildings with fire sprinkler lines.
• Properties with boilers, chemical feed systems, or other high-hazard equipment.

Your water provider keeps track of the assemblies in its system and usually sends a notice when a test is due. Properties that do not comply may receive a compliance notice or have water service interrupted.

Most water providers require a test once a year. Many also want a test when a new assembly is installed and after an assembly is repaired or moved. Your provider's notice is the final word on your deadline, so keep it handy when you call a tester.

A test is a short visit for most assemblies. Here is how it usually goes:

1. The tester looks over the assembly, its shutoff valves, and its test cocks.
2. Water through the assembly is shut off briefly.
3. A calibrated test kit is connected to the test cocks, and each check valve, plus the relief valve on an RPZ, is tested against the required readings.
4. The results go on your water provider's test report form.
5. If the assembly passes, the report is submitted and you are done for the year. If it fails, it needs repair or replacement and a retest.

Only a certified backflow tester. Water providers keep their own rules, and many only accept reports from testers whose certification is current and whose test equipment has been calibrated. The City of Fort Smith, for example, keeps a directory of certified testers and only accepts tests from testers who meet those requirements.

Glenn holds Backflow Testing certification #ATT-1102 and Backflow Repair certification #RT-466, and he is a licensed master plumber, license #5822. Arkansas Backflow & Plumbing is listed in the City of Fort Smith's directory of certified backflow testers.

A failed test is common and usually fixable. Most failures come from debris on a check valve seat or worn rubber parts, and the assembly can be rebuilt on-site with manufacturer-approved parts. If it cannot be repaired, it gets replaced. Either way, it is retested and the updated report goes to your water provider. Our guide on what to do if your backflow test fails walks through it step by step.