Most property managers know there’s a “backflow device” somewhere near the water service, usually because someone sends a reminder that it needs to be tested. Fewer people know what it actually does or why New Jersey takes the annual test seriously.
What backflow is
Under normal conditions, water flows one way: from the public water main into your building. Backflow is when water reverses direction and moves from your building’s piping back toward the public supply.
That can happen in two main ways:
- Back-pressure, when pressure inside your building’s system becomes higher than the supply pressure, such as when a fire department pumps into the system.
- Back-siphonage, when supply pressure drops suddenly, for example during a water main break or heavy hydrant use nearby, and pulls water backward.
Water that has been sitting in fire sprinkler piping isn’t drinking water. It can be stagnant, discolored, and sometimes treated with additives. Letting it flow back into the public supply is a health concern, which is why water utilities and codes require protection on fire service lines.
What a backflow preventer does
A backflow preventer is an assembly installed on the water line that allows water to flow into your system and prevents it from flowing back out. On commercial fire sprinkler services, you’ll typically see one of a few types:
- Double check valve assembly (DCVA). Two independent check valves in series. If one fails, the other is still in place.
- Reduced pressure zone assembly (RPZ or RP). Two check valves with a relief valve between them. If either check valve leaks, the relief valve opens and discharges water to the outside rather than letting it move backward. RPZs are generally used where the potential hazard to the water supply is considered higher.
- Detector assemblies. Versions of the above with a small bypass meter that can reveal unauthorized water use or a leak in the fire line.
Which type you have depends on the hazard, your water utility, and local plumbing rules.
Why New Jersey requires annual testing
Backflow preventers have moving parts: springs, rubber seats, check valves, and relief valves. Debris, mineral buildup, and wear can keep them from sealing. You can’t tell by looking at the outside whether the internal parts are still working, so the assembly has to be tested with gauges.
In New Jersey, the fire code addresses this directly. Section 901.6.4 of the New Jersey Fire Prevention Code requires backflow preventers designed to be field tested to be tested annually in accordance with NFPA 25. The same section says the fire official will accept a current certificate of compliance issued under the Uniform Construction Code for the backflow test, but it also says the fire official shall require a forward flow test to confirm that proper water supply is being maintained for the system’s demand.
That second point is easy to miss. There are really two questions being asked each year:
- Does the device still stop water from flowing backward? This is the backflow test, which looks at the check valves and, on an RPZ, the relief valve.
- Does the device still let enough water flow forward to your sprinklers? This is the forward flow test. A device that seals well but restricts flow can still starve the sprinkler system during a fire.
New Jersey’s plumbing subcode also calls for testable backflow assemblies to be tested before final inspection and annually after that, so you may hear about testing from both your local plumbing official and your fire official.
What happens during a backflow test
A typical test follows a standard procedure:
- The tester connects a calibrated test kit to the test cocks on the assembly.
- The shutoff valves are operated in sequence so each check valve, and the relief valve on an RPZ, can be evaluated.
- Readings are recorded and compared against required values.
- If the device passes, results are documented and submitted as required. If it fails, the report will note which part did not pass so it can be repaired or rebuilt and retested.
During the test, water to the fire system may be briefly shut off. That makes the sprinkler system temporarily impaired, so testing should be coordinated with your monitoring company and building staff, and the system should be confirmed back in service when the work is done.
How to prepare as a property manager
- Know where the device is. It may be in a riser room, mechanical room, or an outdoor enclosure. Make sure it’s accessible and not buried behind storage.
- Check your paperwork. Find last year’s test report and any notices from your water utility or municipality, which often list deadlines and submission requirements.
- Plan for drainage. RPZs can discharge water from the relief valve during testing. Make sure there’s a safe place for that water to go.
- Coordinate the impairment. Notify your monitoring company and tenants of the test window.
- Ask about the forward flow test. Confirm that both the backflow test and the forward flow test are being addressed so you’re covered on both requirements.
Signs your backflow preventer needs attention
Between annual tests, keep an eye out for an RPZ relief valve that drips or discharges, visible leaks or corrosion on the assembly, freezing risk on outdoor or unheated installations, and an unexpected movement on a detector meter. Any of these is worth having checked before the next scheduled test.
Scheduling backflow testing
If your building’s backflow or RPZ test is coming due, or you’d like help understanding a failed report, JT Fire & Safety in Somerville, NJ offers backflow and RPZ testing for commercial fire sprinkler systems. Call (908) 333-2590 to talk through what your building needs.