Backflow testing that protects the drinking water supply

Reduced pressure zone assemblies, often called RPZ or RP assemblies, provide a high level of protection. They use two check valves with a relief valve between them that opens to discharge water if either check fails or pressure conditions become unsafe. They are commonly used where the hazard is significant.

Double check valve assemblies use two independently acting check valves and are typically used for lower hazard applications. Pressure vacuum breaker assemblies protect against back-siphonage and are common on irrigation systems. Spill-resistant vacuum breakers serve similar purposes in certain indoor settings.

Each type has its own test procedure. The tester follows the procedure for that assembly, recording the readings required by the water provider.

Testing uses a differential pressure gauge connected to the assembly's test cocks. With the downstream shutoff closed as the procedure requires, the tester checks whether each check valve holds a minimum pressure difference and, on RPZ assemblies, whether the relief valve opens at the correct point.

The procedure is precise. Readings are compared against required minimums, and the results determine whether the assembly passes. The gauge itself must be accurate, which is why test equipment is calibrated on a regular schedule.

Water service to the protected system is interrupted briefly during testing. We let you know in advance so irrigation, boilers or building operations can be planned around it.

Water providers usually require test results to be submitted on a specific form or through an online system, often within a set period after testing. The report typically includes the assembly type, size, serial number, location, readings, pass or fail status and the tester's certification details.

We complete the documentation and submit or provide it as your provider directs. You receive a copy for your records, which is helpful if the provider has questions or if you need to show compliance later.

Keeping track of annual test dates can be tedious, especially for properties with several assemblies. Maintaining a record of each assembly's history makes scheduling and compliance simpler.

Assemblies fail for many reasons: debris lodged in a check valve, worn rubber parts, weak springs or a relief valve that does not open correctly. A failed test does not necessarily mean the assembly must be replaced.

Many failures are corrected by cleaning and rebuilding the internal components with the manufacturer's repair kit. After repair, the assembly is retested to confirm it passes, and both the failure and the repair are documented.

When an assembly is badly corroded, obsolete or unrepairable, replacement is recommended. The new assembly must be of an approved type for the application, installed in the correct orientation and location, and tested after installation.

Lawn irrigation systems are the most common residential application. Because they connect drinking water to soil, fertilizer and standing water, they almost always require backflow protection, and many providers require annual testing.

Hydronic heating systems with automatic fill valves may have backflow protection on the fill line to keep boiler water, which can contain treatment chemicals, out of the drinking supply. If you have a boiler, our Boiler Repair technicians can check that the fill arrangement and its protection are in good order.

Homes with pools, fire sprinklers, private wells connected to public supply or certain water treatment equipment may also have requirements. Your water provider can confirm what applies to your property.

Irrigation backflow assemblies are often installed outdoors, where freezing weather can crack their bodies or damage internal parts. Before winter, the assembly should be drained according to the manufacturer's instructions or protected as local practice recommends.

In spring, when the irrigation system is reactivated, the assembly is a good candidate for testing. Testing at startup confirms it survived the winter and is ready for the season.

Freeze damage is a common reason for spring test failures. Insulated covers and proper winterization reduce that risk.

An RPZ assembly that discharges water from its relief port is doing its job, signaling a problem. The cause may be a fouled check valve, fluctuating supply pressure or debris. Continuous or frequent discharge should be investigated promptly.

Do not plug or restrict the relief port. Doing so defeats the protection the assembly provides. Assemblies installed indoors need proper drainage to handle discharge without damaging the building.

If you notice discharge, call for testing and repair. The technician will identify the cause and restore the assembly to proper operation.

Backflow testing is priced per assembly, with repairs quoted separately if a test fails. The price is confirmed when you schedule, and repair pricing is explained before any parts are replaced.

Many customers schedule testing when they receive a notice from their water provider. Booking promptly leaves time for any repairs and retesting before the provider's deadline.

For properties with several assemblies, testing can be scheduled on the same visit to reduce disruption.

Backflow protection is matched to the level of risk at each cross-connection. A connection that could introduce a toxic substance calls for a higher level of protection than one that could only affect the taste or appearance of water. Water providers and plumbing codes classify these hazards and specify which assemblies are acceptable for each.

Installation location matters as well. Some assemblies must be installed above grade, some need clearance for testing and repair, and some require a drain nearby to handle relief valve discharge. An assembly installed in the wrong place can be difficult to test, prone to freezing or unable to discharge safely.

When you are adding an irrigation system, a boiler, a pool fill line or equipment that connects to the water supply, ask about backflow requirements early. Planning the protection alongside the project avoids costly changes after an inspection.