Home ownership is all about balancing the features of your home with the amount of time and energy required to maintain them. Your underground sprinkler system is no exception. Along with the convenience of electronically watering your garden, lawn, and flower beds comes the realization that you need to winterize your sprinkler system or it could lead to big problems in the spring. If you live in a mild climate it may not be necessary to winterize. For those who live in the cold-weather climates, you should winterize your system in the fall, generally by the end of October. If you forgot to winterize, didn’t realize it needed to be done, had a life event that kept you from it, or the season just snuck up on you, don’t panic. There are still steps you can take to winterize your sprinkler system mid-winter. If the temperatures are threatening to drop below 30 degrees Fahrenheit it’s time to get to work.
Your sprinkler system’s job is to carry water from one place to another. But when freezing temperatures hit, any water left in the pipes can freeze, expand, and burst your pipes. It can also break valves, spigots, and sprinkler heads, which makes for a major inconvenience when you turn the system on and find puddles quickly forming. When this happens, you need to dig out the lines to replace piping and other parts as needed.
Step 1 - Shut Off Water Supply
Begin by turning off your water supply. This is done at the main valve, wherever that is in your home. It’s usually located in your garage, a utility closet, or basement, but it can be outside as well.
Step 2 - Evaluate
With the water turned off, drain the water from the sprinkler system. If the first deep freeze has already been around for a few weeks, there may not be much you can do at this point except turn off the water and release any pressure valves. By giving the pressure a way to escape you reduce the chances of the pressure blowing out a pipe. Pipes above ground such as those closest to the house are the most susceptible to cold-weather damage.
In areas prone to severely low temperatures, many sprinkler systems are installed 24 to 36 inches below ground. Start by digging through any snow if necessary to find your sprinkler heads and other components of the system. Find out if you’ve already frozen the system by removing a sprinkler head from each zone of your system. If there is ice forming in the opening, then it’s likely the system is already frozen and you will have to wait for spring to see if any damage has occurred. If there is no ice, you can still attempt to blow out the lines.
Step 3 - Blow Out The System
Choose the warmest part of the day for this chore since every degree helps. The majority of homeowners use this technique to prep the sprinkler system for winter. Although it is best done in the fall, you can still use highly compressed air to blow any remaining water out of the lines. For this task, you will want an air compressor with a rating of 80 to 100 for any mainline with a diameter less than 2 inches. If you don’t have an air compressor with that capacity, you can borrow or rent one. Note that landscaping companies may not have their compressors set up in winter since many of them only offer the service seasonally. Also be aware that your household air compressor might not have consistent enough strength to do an adequate job.
Close any open valves, especially those on the backflow device. Remove the blow out cap. There may be pressure built up so use caution. Once you have your compressor, use an adaptor to hook it up to the mainline where the blow out cap was. This is done at the main connection near the backflow device. Make sure you hook it up after the backflow preventer so no air goes through the backflow.
NOTE: Be sure to wear proper eye protection. The compressor is under high pressure and can blow debris into your eyes.
Open the zone located the furthest from the compressor. Do not run the compressor without a valve open or it will cause too much pressure. Open the compressor valve slowly to force air into the sprinkler system. Watch your pressure so that it does not exceed 80 PSI for systems with PVC pipe. If your system has flexible polyethylene piping, keep the pressure below 50 PSI. You don’t want to cause more problems by blowing up a pipe with too much pressure. If there is water in the system, you will see it being forced out of the sprinkler heads, changing from a steady stream to a fine mist or fog to indicate it is clear. Once the first zone appears to be drained, open the next zone in line closer to the compressor and close the one you just finished with. Each zone might take a few minutes to clear. Work your way zone by zone back to the main zone, slowly opening each and waiting for all the water to blow out. Do not run the compressed air through the pipes any longer than necessary because the continued pressure can cause damage.
Once all the zones have been drained, turn off and disconnect the air compressor. Release any excess air from the system by opening the valves on the sprinkler system including those around the backflow protector. Replace your blow out cap loosely to allow room for water to drip out if any enters the system later in the season.
Hopefully you were able to get the water out before it froze in your lines or caused damage. If you were too late, though, know that sprinkler systems are not complicated and repairs are typically something you can handle as soon as the ground begins to thaw.