JoAnne Skelly: Will my drip system freeze?

As I write this, we’re looking forward to a week of lovely autumn weather, possibly with a bit of rain toward the end of the week. However, this article will be published toward the end of the month and it will be time to stop watering plants and drain irrigation systems. A colleague asked me how to winterize the drip system at a school garden she has been working on, a timely fall topic.

Drip systems usually lie above ground and freeze more readily than in-ground systems. Although drip systems are more forgiving than in-ground systems when it comes to freezing, it’s important to protect a system’s timers, filters, fittings, backflow device and electric valves.

To winterize a drip system, start by turning off the water supply to the system. Uncrimp the end caps of the polytubing and completely drain the water out of all parts. This will prevent lines from splitting or being damaged. A good way to drain lines is to blow the water out with compressed air at no more than 30 PSI. If you don’t have an air compressor, raise one end of the polytube above the other and let gravity do the work for you. After draining is complete, cap the ends of the tubes to prevent critters, debris and dirt from getting into them.

Bring the timers, backflow devices, filter regulator assemblies and so on into the house or garage and store them in a place they can’t freeze. Remove any batteries from the timers to prevent corrosion.

To help in the draining process throughout the year, there are flush valves that can be installed at the end of a polytube line or at a low point in the middle. These valves automatically open up when the water pressure inside the tube drops below a certain pressure. A self-draining line reduces potential freeze damage, especially during those early and late freezes.

After everything has been drained, it’s OK to leave the tubing and the emitters outside during the winter. With our winter sun, it doesn’t hurt to cover the lines up with mulch, but it’s not necessary. If you cover the lines, mark their location, so when you start digging in the spring you don’t damage them with a shovel.

Check out all the hook-up parts, timers, filters and valves and replace any O-rings or washers in preparation for next spring. With a little maintenance, a drip system can last for years.

JoAnne Skelly is Associate Professor & Extension Educator, Emerita at University of Nevada Cooperative Extension. She can be reached at


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