If you live in a region where temperatures drop below freezing, you need to know how to winterize backflow preventer devices to avoid costly damage and keep your drinking water safe. Winterizing a backflow preventer is a critical maintenance step that prevents ice from cracking the internal check valves, relief valves, and housing. In this guide, we’ll walk you through the exact process, tools required, and common mistakes to avoid, so your backflow preventer survives the winter and continues to protect your water supply.
What Is a Backflow Preventer and Why Does It Freeze?
A backflow preventer is a mechanical device that stops water from flowing backward from your irrigation system or other non-potable sources into your home’s clean water lines. Most residential backflow preventers are installed outdoors, either as a pressure vacuum breaker (PVB) or a double check valve assembly (DCVA). Because they contain water and are exposed to outdoor temperatures, they are highly susceptible to freezing. When water freezes, it expands by about 9%, which can crack metal or plastic components, rendering the device useless and potentially causing water damage to your property.
When Should You Winterize Your Backflow Preventer?
The ideal time to winterize is before the first hard freeze of the season—usually in late fall, when nighttime temperatures consistently drop below 32°F (0°C). In most northern US states, this means late October to mid-November. If you wait until after a freeze, the damage may already be done. Check your local weather forecast and plan accordingly.
Tools and Materials You’ll Need
Before starting, gather the following items:
- Adjustable wrench or pliers
- Flathead screwdriver
- Bucket or pan to catch water
- Teflon tape
- Pipe insulation foam (for exposed pipes)
- Backflow preventer cover or insulated blanket (optional)
- Owner’s manual for your specific model (if available)
Step-by-Step: How to Winterize a Backflow Preventer
Follow these steps carefully. If your device is complex or you’re unsure about any step, contact a licensed plumber for assistance.
Step 1: Shut Off the Water Supply
Locate the main shut-off valve for your irrigation system or the isolation valve on the backflow preventer itself. Turn it clockwise until it’s fully closed. This stops the flow of water into the device.
Step 2: Release Pressure
Open any test cocks (small valves on the side of the device) and the relief valve (if present) to release trapped pressure. Use a bucket to catch any water that drains out. Leave the test cocks open for now.
Step 3: Drain All Water
Remove the caps on the test cocks and allow all water to drain completely. For PVB devices, you may need to tilt the device slightly to ensure all water escapes. For DCVA models, open the ball valves and drain any remaining water. If there’s a low-point drain on your system, open that as well.
Step 4: Insulate Exposed Pipes and Valves
Once the device is dry, wrap any exposed pipes and valves with foam pipe insulation. This adds a layer of protection against residual moisture and temperature fluctuations. If your area experiences severe cold, consider installing a specially designed backflow preventer cover.
Step 5: Store the Device Indoors (If Removable)
Some backflow preventers, especially PVBs, can be unbolted from the piping and stored indoors for the winter. If your model is removable, disconnect it, cap the open pipes, and store the device in a frost-free location like a garage or basement. This is the most reliable method to prevent freezing.
Step 6: Label and Record
After winterizing, place a tag or label on the shut-off valve reminding you to reopen it in the spring. Also, note the date and any maintenance steps in your home maintenance log.
Winterization Tips for Different Types of Backflow Preventers
Different devices have unique requirements. Here’s a quick comparison:
| Type | Common Use | Winterization Steps |
|---|---|---|
| Pressure Vacuum Breaker (PVB) | Residential irrigation | Shut off water, open test cocks, drain completely, remove and store indoors if possible. |
| Double Check Valve Assembly (DCVA) | Commercial or high-risk residential | Shut off both isolation valves, open test cocks, drain, leave test cocks open. |
| Reduced Pressure Zone (RPZ) | Commercial or high-hazard applications | Shut off inlet and outlet valves, open relief valve and test cocks, drain. Consider professional service. |
Common Mistakes to Avoid When Winterizing
Even experienced DIYers make errors. Here are the most common pitfalls:
- Leaving water in the device: Even a small amount can freeze and crack the housing.
- Forgetting to open test cocks: Trapped pressure can cause seals to fail.
- Not insulating after draining: Residual moisture can still freeze.
- Reopening the water supply too early: Wait until all danger of frost has passed.
- Skipping annual professional inspection: Even if you winterize, a yearly check by a licensed plumber ensures the device is functioning correctly.
Why Winterizing Is Critical for Water Safety
Backflow preventers are your first line of defense against contamination. If they crack or fail, contaminated water from irrigation, pools, or other sources can siphon back into your home’s drinking water. According to the EPA WaterSense program, proper maintenance of plumbing devices is essential for water quality and conservation. Additionally, the CDC emphasizes the importance of preventing backflow to avoid waterborne illnesses. By winterizing correctly, you protect both your investment and your family’s health.
When to Call a Professional Plumber
While winterizing is often a DIY task, some situations require professional help. If you notice any of the following, contact a leak detection specialist or pipe repair expert:
- Visible cracks or damage to the device
- Water leaks around the backflow preventer
- Difficulty shutting off or opening valves
- Complex RPZ assemblies that require specialized tools
- Local codes requiring certified technicians for winterization
Frequently Asked Questions
Can I use antifreeze to winterize my backflow preventer?
No. Antifreeze is toxic and can contaminate your water supply. Always drain the device completely and avoid using any chemical additives. If you need extra protection, use insulation or move the device indoors.
How often should I winterize my backflow preventer?
In cold climates, you should winterize every year before the first freeze. In milder climates, you may only need to do it if temperatures are expected to drop below freezing for an extended period.
What happens if I forget to winterize my backflow preventer?
If the device freezes, it can crack, leading to leaks and potential water damage. It may also fail to prevent backflow, compromising water safety. You’ll likely need to replace the device, which can cost anywhere from $150 to $500 for parts and labor, depending on the type and local rates. (Prices vary by region and plumber.)
Do I need to winterize a backflow preventer that is indoors?
If the device is installed in a heated indoor space (e.g., a basement or utility closet), winterization is usually not required. However, if the space is unheated (like a garage), you should still drain it or insulate it.
Can I winterize a backflow preventer myself, or should I hire a plumber?
For simple PVB or DCVA models, DIY is possible if you’re comfortable with basic tools. For RPZ assemblies or if you’re unsure, hiring a licensed plumber is safer and ensures compliance with local codes.
How do I know if my backflow preventer needs repair after winter?
In the spring, before reopening the water supply, inspect the device for cracks, leaks, or corrosion. You can also perform a simple test: open the shut-off valve and check for drips from the relief valve. If you notice any issues, call a professional for water heater repair or backflow service.
Final Tips and Maintenance Schedule
To keep your backflow preventer in top shape, follow this yearly schedule:
- Fall: Winterize before first freeze.
- Spring: Reopen valves, check for leaks, and test the device.
- Summer: Inspect monthly during irrigation season.
- Annual: Schedule a professional inspection and testing (required in many municipalities).
By following this guide, you’ll save money on costly repairs and ensure your water stays safe. If you need professional assistance, don’t hesitate to reach out to the MyTownPlumber team for expert plumbing services.