How to Winterize Irrigation System: 10 Tasks for Winter


Irrigation systems can become seriously damaged and cause lots of problems if not properly prepared for freezing winter weather. There are several steps to take when winterizing an irrigation system, which will help ensure it lasts longer and doesn’t cause any problems during those long, cold winter months that could be costly, dangerous, and stressful to deal with.

Here are the ten to-do tasks in how to winterize an irrigation system:

1. Turn off the irrigation system

Before temperatures reach below freezing, turn off the main water supply for the irrigation system. If these steps are not taken before freezing occur, there is a risk that the PVC or polyethylene piping that has been used could crack and burst.

2. Turn off automated timers

If the irrigation system is set on a timer, it is important to make sure this is off, so that the system doesn’t try to irrigate during freezing weather. To do this, set the controller to off or rain mode, which will maintain all of the settings that have already been selected throughout the winter, but won’t actually activate the system.

Alternatively, the power to the transformer can be shut down, but this will cause the loss of all settings that had previously been used

3. Insulate the shut-off valve

In order to winterize the irrigation system, the shut-off valve must be insulated so that it doesn’t freeze. This can be done using insulation, pine straw, or any other insulating material, as long as it protects the valve against the cold.

4. Insulate above-ground piping

Above ground piping must also be insulated. The insulation will help to control the expanding and contracting of the pipe when the temperature fluctuates. For this, there are several supplies that can be found at any home hardware and supplies store that will do the trick. Common solutions are self-adhesive foam insulation and foam insulating tubes.

5. Protecting the rain sensor

If the irrigation system has a rain sensor which contains a small cup for catching water, that cup should be emptied so that it does not freeze. Then, a little bag or covering of some sort can be used to further protect the sensor from moisture and freezing over the winter. In addition, you should also protect other key components such as the irrigation filter.

6. Drain the pipes

The biggest risk for pipes in the winter is if there is any water left inside of them when freezing occurs. There are a few methods for draining out irrigation system pipes to prepare them for the winter months.

7. Manual drain

One method for draining irrigation pipes is a manual drain. This method is used when the system has manual valves located at the ends and at the low points of the irrigation system. Locate the manual drain valves and open them all. This will drain the water out of the mainline. The system will have either a boiler drain valve or a stop and waste valve.

Whichever the system has, open it and allow the rest of the water to drain out. If the sprinklers have check valves, they too must be drained by lifting them up, and the test cocks on the backflow unit must be opened. Once this is all done, close up all the valves you opened.

8. Automatic drain

If the system contains automatic drain valves at the end or low points of the irrigation piping, then the automatic drain method will be used. The automatic drain valves will begin their work when the pressure on the system drops below 10 PSI, which will occur once the system is shut off completely and the system pressure is relieved.

After that, the rest is the same as the manual drain  – the boiler drain valve or stop waste valve must be opened, the test cocks must be opened, and the sprinklers may need to be lifted and drained as well.

9. Blow out drain

This is a more dangerous method, because the compressed air used could send debris flying that can injure an individual. It is necessary that those using this method wear protective gear, including eyewear. Connect an air compressor with a Cubic Foot per Minute rating of approximately 80 to 100 to the mainline. Begin with the system turned off.

Start with the part of the system that is farthest away from the compressor and which has the highest elevation, and work towards the compressor. Slowly introduce the compressed air into the system, never exceeding a pressure of 80 PSI. Stop as soon as all of the water has been blown out, or it could do more harm than good.

10. Call in an expert

To make sure that the job gets done correctly and safely, it may be best to call in a professional, especially for draining the system using the blow out method. Making a mistake here could cause costly damage to the irrigation system, so if there is any uncertainty, it might be worth paying first to avoid having to pay more later.