How To Winterize a Backflow Preventer Valve In 8 Steps (or 1)

Cold weather is your sprinkler system's enemy. Every year, homeowners and water jurisdictions get caught off guard by sudden freezes that cause unexpected damage to outdoor plumbing.

If you’ve never winterized a backflow preventer before (or aren’t sure if you’ve done it right), here are some tips to save you major headaches when temperatures drop.

Why Winterize Your Backflow Device?

By winterizing your backflow preventer, you're protecting plumbing equipment and avoiding costly repairs. Frozen water expands, creating pressure that can crack valves and seals, and this improper winterization can lead to contamination of the water supply. Spending time on winterization ultimately saves time, money and stress so you're not biting your nails until the return of spring.

While summer is a good time to think about winterization — because working on malfunctioning equipment or negotiating with frozen pipes and valves in the cold is unpleasant — it's never too late to get started.

Advice you may have heard includes using pipe sleeves or a protective cover to block wind and moisture. Or, hiring a professional winterization service and crew to ensure the backflow preventer is properly drained and insulated to prevent freezing, which can be useful if the backflow preventer is difficult to access.

But protective foam covers and tips like leaving valves slightly open after draining your line are not foolproof winterization methods. To fully prevent damage during freezing temperatures, you should remove the backflow preventer entirely.

8 Steps to Winterize Your Backflow

Here's a handy checklist to remove your sprinkler system's backflow device properly.

1. Shut off the water to the sprinkler system and backflow preventer at the main valve.

2. Turn sillcock valves (faucets) to open; drain all water still in the line. Draining all water from the device includes opening the test cocks and system-side ball valve.

3. Connect a high-volume air compressor and turn it on. For irrigation systems, a compressor set to 30-50 psi is recommended.

4. Turn on faucets or, if needed, activate each irrigation system zone, until only air comes out.

5. Turn the valves on either side of the backflow preventer to a 45-degree angle after draining.

6. Stop the air compressor and disconnect it from the system.

7. Remove the backflow and store in a safe location.

8. Apply petroleum jelly to union seals and wrap seals with plastic to prevent animals and debris from entering the lines.

This process takes time and effort, both of which would otherwise be better spent doing just about anything else. But, hey, you do what you have to do to make sure your system is winterized, right?

Properly Winterize Your Backflow Preventer the Easy Way

There's another effective option. It saves time, is cost-effective and hassle-free. Plus, you only have to do this once, not every year.

The answer? Install an insulated enclosure over the backflow device to protect it from cold and moisture.

When your device is protected inside a heated enclosure, you won't have to assemble and disassemble backflow preventers each season. Aluminum enclosures have weatherproof insulation,and are completely closed and locked over your backflow preventer to prevent damage and vandalism. Adding a heater ensures the enclosure maintains above freezing temperatures during winter.

Check our sizing guide to find the right aluminum enclosure for your backflow preventer.

FAQ: Backflow Preventer Valve Winterization

Why is it important to winterize a backflow preventer?

Winterizing a backflow preventer helps prevent frozen pipes, cracked valves, and costly water damage caused by freezing temperatures.

When is a good time to winterize a backflow device?

It’s best to winterize your backflow before the first hard freeze — typically in late summer or early fall — so you’re not dealing with frozen components in winter. The information in this article gives tips to properly winterize your backflow device to ensure potable water throughout the winter.

Is an insulated backflow enclosure an alternative to full winterization?

Yes. An insulated enclosure with a built-in heater can protect your backflow preventer, pressure vacuum breaker, and irrigation systems from freezing without requiring full removal, draining the drain valve or line blowout.

What are the benefits of using an insulated backflow cover with a heater?

Insulated enclosures save time, reduce labor, protect equipment all winter, and provide a convenient, long-term solution compared to winterization steps that require removing the backflow.