How to Winterize Your Sprinkler System

If you’ve got an automatic sprinkler system installed in your yard, its probably been used at least weekly to keep your lawn green and hydrated. When summer turns into fall, you’ll need to winterize your sprinkler system along with other essential cold-weather tasks on your list. Before you know it, temperatures will drop to below freezing, and if you don’t make sure your sprinkler winterization is done, any water left in your pipes will freeze, which could cause significant damage.

Using this step-by-step DIY guide on how to winterize your sprinkler system will help save you the headache and financial cost of replacing your system after winter is done.

How to winterize sprinklers, step by step

Sprinkler systems come with either manual valves or automatic valves. Before starting, determine which one is installed on your property. Automatic sprinkler valves automatically drain water from the pipes if the pressure falls below a specific setting, while manual sprinkler valves simply drain water after one of the valves is open.

Step 1: Shut off the water supply

Similar to working on any plumbing in your home, you must shut off the water supply first to avoid flooding your lawn. You can usually find the water supply inside the home in close proximity to the water heater. Once you’ve found the water main, close the valve. The valve will usually be red or blue in color and should be marked appropriately, letting you know you’re shutting off water to your property.

When you winterize your sprinkler system, take extra steps to prevent water from entering the system. To do this, find the pipe that leads off the water main and feeds your sprinkler. Then, turn off the water supply using the valve on the pipe, similar to how you turned off the water main.

The homebuilder or previous owner should have marked each pipe with where it leads. For example, the one that leads to the sprinkler hopefully says “sprinkler,” and the one that leads to the house might say “house.” If not, now is a good time to make a note of which pipe leads where.

Step 2: Turn off your automatic activation system

If your yard is equipped with an automatic sprinkler system, turn the system off. Do this by finding the system’s controller and choosing the right setting. For modern systems, use the “rain mode” setting to deactivate the system. If you have a system that uses analog dials, turn the dial to the “off” position.

Pro tip: If your system does have a “rain mode,” make sure to use it instead of turning it all the way off. This prevents the loss of any personalized settings that were programmed when the system was installed.

Step 3: Drain your pipes of any excess water

Make sure all water is removed from the pipes. You can do this by draining the pipes manually or blowing out the system. When you blow out the sprinkler system, you pump compressed air through the pipes to push out any excess water.

To drain pipes manually:

Find the bleed valve or manual drain valve on the sprinkler system and open it. You can normally find the bleed valve on the side of the house where the pipes come up from the ground. When performing this step, make sure to have a bucket handy ready to catch any water that comes out.

Blow out your sprinkler system:

Learning how to blow out sprinklers can be daunting at first, especially if you’ve never used an air compressor.  You’ll start the blowout process by closing the backflow preventer valve and removing the plug that’s screwed into the side of the port. Then, use a quick connect blowout plug to attach the air compressor hose to the plug.

Find out how much air the system can handle by finding the gallons-per-minute, or GPM, of each sprinkler head, and dividing the total GPM of each zone by 7.5. Open up one zone in the system and turn on the compressor to expel the water in that zone.

Once you notice the sprinkler head pop up and water come out, turn off the compressor, so you don’t damage the system. Repeat this step for every zone, making sure to open only one zone at a time.

Tools you’ll need to winterize sprinkler systems

• Gloves: A good pair of work gloves to protect your hands and make the job easier.
• Air compressor: You’ll want an air compressor, so you can blow out your sprinkler system. Note that many do not come with a hose.
• Quick-connect hose adapter: You’ll need a hose adapter  to connect the hose to the system. A quick-connect hose adapter kit usually comes with numerous adapters of different sizes.
• Air compressor hose: An air compressor hose connects the compressor to the sprinkler system.
• Screwdriver:  You’ll want a variety of screwdrivers in case you run into problems when opening your valves.
• Wrench: Depending on your valves, a wrench might come in handy. A wrench set should include pliers, wrench, and vice grips.

How to determine if you should hire a professional

DIY sprinkler winterization can be a daunting task, especially if you’re unfamiliar with the system on your property, or you don’t have access to the right tools. If you don’t feel comfortable learning how to blow out sprinklers, hire a professional.

Depending on where you live, the average cost to winterize a sprinkler system can run between $50 and $150 for the entire project. The size of your system might affect the price as well.

The bottom line

While sprinkler winterization should only be a half-day project, inexperienced homeowners might find it difficult to locate valves and determine how much air should be used during the blowout process. If this is your first DIY winterization, consult with a professional first to avoid costly mistakes.

To avoid disastrous pipe and system freezes, make sure to winterize your sprinkler system well ahead of the first frost. Always take precautions when working outside, under the house, or with any type of tools.

Frequently Asked Questions

How do I drain my sprinkler system for winter? 

Check the system instructions for the best drainage practices. When using a manual drain valve, you’ll open valves in each zone to let the water drain out. For automatic drain valves, open the drain cap near the backflow device and then lift each sprinkler head to drain out water. If you’re careful, using an air compressor can speed up the process.

How much does it cost to winterize your sprinkler system? 

If you hire a professional, expect to pay north of $150, depending on where you live and the size of the system. If you complete the project yourself and need to purchase tools, you’ll likely spend anywhere between $200 and $300 for everything you need.

How do I find the pipe that feeds the sprinkler system? 

The pipe that feeds into the sprinkler system is connected to the water main close to the main shutoff valve with a T-shaped connector.

How big of an air compressor do I need? 

Depending on the size of your system, you might need to purchase or rent a compressor with an output capacity of up to 10 CFM (cubic-feet-per-minute).