Protecting Your Backflow Preventer From a Fort Worth Freeze

North Texas winters are usually mild, but hard freezes do happen, and they can arrive with only a few days’ warning. When they do, the backflow preventer is the part of your sprinkler system most at risk. It sits above ground, it is made of metal that conducts cold, and it holds water. This article explains how to protect it before a freeze and what to check afterward.

Why the Backflow Preventer Is at Risk

Most of your sprinkler system is buried, and the soil protects it from brief cold snaps. The backflow preventer is installed above ground so it can be tested and so it drains properly. That means it is exposed to the air. When water inside it freezes, it expands and can crack the brass body, split internal parts or push out seals. The damage often does not show until the system is turned back on and water starts spraying.

Fort Worth saw how damaging a long freeze can be during the February 2021 winter storm, when many homes had frozen and broken pipes. Even shorter freezes can crack an unprotected assembly.

When to Take Action

Watch the forecast in winter. Take steps when:

• A hard freeze is forecast, especially with temperatures staying below freezing for several hours
• Freezing temperatures are expected on more than one night in a row
• Strong wind is forecast along with cold, since wind speeds up heat loss

A single light frost for an hour or two is less of a threat, but protecting the assembly is still a good idea.

Option 1: Insulate It

For short freezes, an insulated cover can be enough. Options include:

• A fitted insulated backflow cover or bag made for this purpose
• Pipe insulation on exposed pipe leading into and out of the assembly
• An old blanket or towels wrapped around the assembly and then covered with a plastic bag to keep the insulation dry

Make sure the insulation covers the whole assembly, including the pipe where it comes out of the ground. Remove wet towels after the freeze so they do not stay damp against the brass.

Option 2: Shut Off and Drain

For hard freezes or longer cold stretches, shutting off and draining the assembly offers more protection:

1. Close the irrigation isolation valve upstream of the backflow preventer, usually between the meter and the assembly.
2. Close the two shutoff valves on the backflow preventer by turning the handles perpendicular to the pipe.
3. Open the test cocks slowly with a flat screwdriver to let trapped water drain out. Some water will spray at first.
4. Leave the shutoff valves partly open, at about a 45-degree angle, so water is not trapped in the valve balls. Some manufacturers recommend this; check yours.
5. Insulate the drained assembly as well.

Turn the controller off or set it to off while the water is shut off. Our guide to winterizing a sprinkler system covers the rest of the system.

Option 3: Both

For the hardest freezes, drain the assembly and insulate it. This is what many technicians recommend when a multi-day freeze is forecast.

What Not to Do

• Do not use heat lamps, space heaters or open flames near the assembly. They are a fire risk.
• Do not wrap the assembly in plastic alone. Plastic does not insulate.
• Do not run the sprinklers during freezing weather. Water on sidewalks and streets can turn to ice. A working freeze sensor helps prevent this. See our article on rain and freeze sensors.
• Do not forget to close the test cocks before turning the water back on.

After the Freeze

When temperatures are safely above freezing:

1. Close the test cocks.
2. Open the irrigation isolation valve slowly.
3. Open the backflow shutoff valves slowly.
4. Watch the assembly for a minute or two for drips, sprays or cracks.
5. Run each zone briefly and look for leaks.

If you see water leaking from the body or fittings, shut the water off again and see our article on a leaking backflow preventer. For damage elsewhere in the system, read our guide to freeze damage after a hard freeze.

If It Cracked

A cracked assembly needs repair or replacement. In Fort Worth, replacements require a plumbing backflow permit, and any repaired or replaced assembly must be tested by a registered Backflow Prevention Assembly Tester. Plan ahead: after a widespread freeze, many homes need the same work at once.

Long-Term Protection

• Keep an insulated cover on hand before winter arrives.
• Learn where your isolation valve is and make sure it turns freely.
• Consider a permanent insulated enclosure that lifts off for testing.
• Make sure the assembly is not buried or sealed in, since it needs access and drainage.

Other Exposed Parts to Protect

The backflow preventer is the main concern, but it is not the only part above ground. Check for exposed pipe where the supply line rises out of the ground to the assembly, above-ground valves on some older systems, hose bibs and any irrigation pipe that runs along a wall. Wrap exposed pipe with foam pipe insulation. Disconnect garden hoses from outdoor faucets so water does not freeze in the faucet. Covering hose bibs with insulated faucet covers helps too. These small steps take a few minutes and protect parts that are expensive to replace after a freeze.

When to Call a Technician

If you are not comfortable draining the assembly, cannot find the isolation valve, or the assembly cracked, our sprinkler repair team can help.