How to Winterize Your Sprinkler System

Without the right preparation, freezing temperatures can cause pipes and sprinkler heads to freeze and break, leading to costly repairs. 

The good news?

A little winterizing can easily prevent all that.

What is winterization?

Winterization is the process of preparing your sprinkler system for the winter, i.e., to withstand freezing temperatures.

Any water in your sprinkler system could freeze and crack pipes, causing costly damage. So when you winterize your sprinkler system, you turn off the water and clear out any water left in the pipes, valves, and sprinkler heads. 

Why is winterizing your sprinkler system important?

When water freezes, it expands. And that expansion can lead to cracked pipes and broken sprinkler heads.

Winterizing ensures your system is safely shut down for the season, protecting your investment and keeping it in good shape for when the warmer months return.

It’s a necessary step for maintaining a long-lasting sprinkler system and avoiding preventable repair costs.

When to winterize your sprinkler system

Timing is critical when it comes to protecting your sprinkler system from the cold. The best time to winterize is before the season’s first freeze.

Here in the Portland area, the first freeze is typically around the first week of November. Check to see when the first freeze typically occurs in your region.

Keep an eye on the weather forecast as temperatures start to drop. A good rule of thumb is to winterize your system before the overnight temperatures consistently dip to 32°F or below.

Waiting too long could expose your pipes and sprinkler heads to freezing conditions, which is exactly what you’re trying to avoid. 

If you’re not sure when to winterize, remember that it’s always best to be a little early rather than too late. Once your system is prepped for winter, you can rest easy knowing it’s protected, no matter when the first frost hits.

How to winterize your sprinkler system

Here’s a step-by-step guide to winterizing your sprinkler system properly:

Tools you’ll need:

• Air compressor (with extension cord)
• Air hose quick coupler with ½” male threads
• Air hose
• Short-handled flat-head screwdriver

Step-by-step sprinkler winterization

1. Locate your backflow prevention device

This is typically found in your front yard, in a valve box underground. This device keeps your drinking water supply safe by preventing contaminated water from flowing back into it. This is what a backflow prevention device looks like:

2. Turn off the water

Turn off the water to the backflow prevention device. This will shut off all water to the sprinkler system. There’ll typically be a special valve (red arrow) for shutting off the sprinkler system. In most cases it’s located in a smaller valve box on the street side of the backflow prevention device.

It may also be located in the same valve box as the backflow prevention device. If you can’t find a separate shutoff valve, use the blue-handled valve on the backflow device itself to turn off the water.

3. Drain the low points

If your system has low-point drains, open them now to let any excess water escape from those areas.

4. Prepare the test cocks

Locate the four round, black test cock caps on the backflow prevention device. Locate the furthest downstream valve, typically the one closest to the house, not the street.. Remove its cap and, using your flat-head screwdriver, slowly turn the screw head slot ¼ of a turn. Be careful as water may shoot out briefly but will stop. Leave the test cock open for now.

5. Connect the air compressor

Now comes the tricky part. Attach the air hose coupler to the test cock. Finding the right-sized fitting can be challenging – you might need to make a few trips to the hardware store to get it right.

Turning your sprinkler back on in the spring

Once you’ve said goodbye to the winter and freezing temperatures, here’s how to safely get your sprinkler system back up and running:

1. Close all low-point drain valves – Before turning the system on, make sure any low-point drains are closed.
2. Slowly turn on the main valve – Open the system’s main valve to let water fill the pipes. It’s important that you let the water slowly bleed into the system for about a minute. Turning the water on too quickly can create a pressure surge that may crack pipes.
3. Run and inspect each zone – Using your controller, test each zone to ensure proper coverage. You may need to adjust sprinkler heads and nozzles if plant growth or winter shifts have affected water flow. Keep an eye out for any leaks or damaged pipes, and repair them as needed.
4. Make any adjustments – Sometimes buried heads need to be raised, or nozzles adjusted to accommodate changes in your yard. Sprinkler heads are typically attached to flexible hoses, so lifting them without breaking them should be easy once they’re exposed.
5. Review controller settings – If the weather is still cool or rainy, leave the controller off, but make sure the programming is correct for springtime conditions. Your sprinkler system is now ready for spring!
6. Backflow testing – Many municipalities require annual backflow testing. This ensures your drinking water is protected from contaminants and needs to be performed by a professional.

Common mistakes when winterizing sprinkler systems

While winterizing your sprinkler system is relatively easy, it’s easy to make mistakes if you’re not careful. Here are some common mistakes to watch out for and avoid:

• Forgetting to shut off the water before starting leads to water being left in the pipes which can then freeze and cause damage. 
• Using too much air pressure can damage your pipes, valves, and sprinkler heads. Keep air pressure below 60 psi. 
• Not fully draining the system and clearing low-point drains results in leftover water – which we already know is bad. 
• Neglecting the backflow prevention device. Your backflow prevention device also needs to be winterized. It needs to be drained or blown out, or it could freeze and crack.
• Starting too late puts you at risk of damaging your system. You need to winterize before the first freeze. 
• Not calling a professional for complex systems. If your system has multiple zones, specialized components, or is difficult to access, consider calling a professional to help you ensure it’s properly winterized.

Winterize Your Sprinkler System for Longevity 

Sprinkler systems can last for years if properly maintained. If you have any questions about proper care, contact a licensed landscape contractor for assistance. Many contractors offer sprinkler winterization as a service.

Blessing Landscapes offers comprehensive sprinkler services, from installation to adjustments to winterization.  Contact us to find out how we can serve your irrigation needs.