How To Winterize Sprinkler System

The dreaded winter season is finally over. It’s time to get the lawn back to its lush-green attractive state. But the sprinkler system won’t work. It could be one of many things - the sprinkler heads, anti-siphon devices, pipes, or valves could have been damaged by the freezing temperatures.

Not good; now you need to replace the part that’s cracked or maybe even the whole system.

But let’s rewind and choose option B instead.

Winter is coming; you winterize your sprinkler system throughout the cold season. You bring it back on when spring comes. The system works properly, and you have a luxurious green lawn in no time.

The second option sounds much better, especially if you live in a place where the frost line goes below the pipes’ level in the ground. Let’s talk about how you can get your pipes ready for the cold season.

Why You Need to Winterize Your Sprinkler System

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If you live where the ground temperatures drop well below freezing point, your irrigation system is susceptible to damage and cracks because of the cold temperature.

Most pipes are made from rigid PVC or flexible Poly pipes. Both these materials can crack, tear or burst under pressure.

If the water freezes inside the pipes, it will expand and push out against the pipes’ walls exerting too much pressure, which causes the pipes to break. The sprinkler heads and valve are also not designed to withstand frozen water and may suffer the same fate as the pipes.

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To avoid facing any crack, or burst-related problems in the pipes and manifold, you need to start preparing for the cold season well before temperatures drop below 32 degrees Fahrenheit.

A good rule of thumb is to winterize your irrigation system as soon as the fall season ends. You will need to observe the weather patterns in your area around late fall to early winter, so an early freeze doesn’t catch you off guard.

The Sprinkler Winterizing Process

Winterizing the sprinkler system involves removing all the remaining water from the system to prevent ice damage. Here’s how.

Step 1: Turn off the Water and Shut the Valves

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Before you do anything else, you need to shut off the water from the main water supply. If your system has backflow preventing valves connected to the backflow device, you also need to shut off these valves too.

Step 2: Set the Timer to Rain Mode

Orbit - 58910 - 1-Dial 2-Port Hose Faucet Timer

If your sprinkler system uses a timer, set the timer to rain mode. That way, you put the timer to sleep without losing your settings. If that’s not an option, you can simply switch off the timer.

Step 3: Remove Any Water Left in the Pipes 

Stopping the water supply into the system is not enough; you will need to make sure the irrigation system is completely drained. There are a few methods you can use to drain all the water out of the system.

Automatic Drain

Some sprinkler systems allow you to drain the water automatically. All you need to do is:

• Turn on the sprinklers with the water supply still cut off 
• Loosen the solenoid (pictured below) on each valve 

Hunter - 606800 - Replacement 24V Solenoid

The system will drain the water out.

Manual Drain 

Here you need to open each valve and let the water flow out manually. Manual drains systems usually have a shut-off valve (like the one in the picture below) at the ends of the piping. When you open the manual drain valve, the water should drain out of the piping. 

Netafim - T12SOV - 12mm Shut-Off Valve

Note: Use eye protection when you open or loosen valves; the water pressure may damage your eyes.

Blowout Drain

The blowout method is the most effective sprinkler system draining method. With this one, you use compressed air to force the water out of the piping. The high air pressure will blow all the water out until there’s no water left. Here are the steps to follow when using the blowout method.

1. Get an air compressor with a volume of 80 - 100 cubic feet per minute. Any compressor that can’t generate this volume won’t be able to blow the water out completely. You may need to hire a compressor since most home compressors don’t generate this kind of volume.
2. Hook the air compressor to the sprinkler system using the hose bib or quick-connect coupler. Be sure to attach it after the backflow device as the air pressure could damage the backflow preventer.
   

   
   Toro - 100-2SLVC - 1

3. Turn on the irrigation station that’s elevated higher than the rest and is farthest from the air compressor.
4. Close the backflow isolation valves.
   

   
   Conbraco - 4A-505-02(F)

5. Slowly open the compressor valve to start introducing air into the valve.
6. Progressively add more air pressure until the water starts coming through. Remember not to put too much pressure all at once as this could cause damage to the piping.

Note: Maintain the air blow pressure below the maximum operating pressure of the lowest-rated part of your system. For example, if your irrigation system’s lowest-rated component has a pressure specification of 50 PSI, don’t open the compressor above this specified pressure.

Generally, stick to 80 PSI for PVC piping or 50 PSI if you have polyethylene piping.

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7. Starting with the sprinkler head farthest from the compressor, open each sprinkler head in turn. Now repeat this process on each head, working your way from zone to zone as you move to the zone nearest to the air compressor.

Blow out each station for about 2 minutes. Once you make sure that the spray of water out of the sprinkler head had stopped, shut off the head and move on to the next.

Don’t keep blowing air through the irrigation pipes longer than you should to avoid the compressed air tearing the dry pipes.

8. When you’ve gone through all the irrigation stations, switch off the compressor and disconnect it.
9. Release any pressure left inside the irrigation system by opening and closing the valves a few times on the backflow device or manual drain valve.
10. Close all the valves.

At this point, your work is done, and the irrigation system should be completely dry.

Safety tip: Keep your eye protection on throughout the process; both the water and air blow have incredibly high pressure and may be dangerous, especially for your eyes. Also, don’t run the compressor unless at least one control valve is open.

Insulate the Irrigation System

The final step is to cover all the components above ground with insulation tape or foam covers to prevent them from freezing. This includes:

• The main water supply shut off valve
• Backflow preventers (Make sure to leave air vents open)
• Exposed parts of the pipes

Taking Care of Your Lawn Sprinkler System 

Winterizing your sprinkler system is the best way to protect your investment in your irrigation system. If you do it right and on time, your system will be as good as new, ready to keep your lawn looking magnificent when spring hits.

Need any help winterizing your system? Get in touch with the Sprinkler Supply Store. We’re more than ready to help you put your irrigation system to bed for the winter and give you expert advice to keep your sprinkler system going strong for longer.