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Features Agronomy
10 steps to winterize an irrigation system

October 9, 2012  By Lorne Haveruk

Fall shut-down procedures

“No matter how much we wish and pray, we cannot keep old man winter away.”

Many parts of the country have experienced a summer than began OK and
went extremely hot and dry and now is cooling with resulting rainfall.
It’s already time to prepare to winterize your irrigation system. This
step of irrigation management is usually best left to the

It has never been truer “you get what you pay for” than in the spring when you cross your fingers and pressurize your irrigation system for the first time that season. Even if it has been properly winterized by a professional irrigation contracting company, you may still encounter some kind of problem. Most companies repair what freezing has damaged if you have a contract with them as long as they did the winterization, and no one has touched the water controls. irrigationwebFailure of components that are installed to keep the water from entering the system is unfortunate but not uncommon. Water seems to somehow find its way into sealed spaces. It’s the mystery of the water business.


It is rare to find an automatic irrigation system that the owner does not have winterized and remains intact. As we all are fully aware of, water when frozen expands. Water trapped inside of a valve chamber, PVC pipe, or manual ball valves tends to crack these components. PVC pipe has been known to herringbone (crack into many long splinter pieces) the full 20-foot length of a PVC pipe and sometimes goes past the bell end and continues down the next pipe.
Damage caused from water freezing is expensive to repair and is many times the cost of a professional fall shutdown. So don’t delay and be sure your system(s) is winterized before it freezes. This usually takes five days of minus 5 degrees Celsius to freeze the pipes.

Putting your irrigation system to sleep for the winter…use this 10 step method


To winterize a residential and small commercial system properly (large commercial and golf systems differ slightly due to the size and length of the pipes), the following steps need to be adhered to:

1. Turn off all water sources to the irrigation system …city water or pumps systems.

2. Use an air compressor that has a large volume of air at a lower operating pressure than most air compressors are set at. For residential and small commercial a 185-cubic-feet-per-minute (CFM) air compressor set at 75 to 90 psi is desirable. Large commercial sites require a 250-cfm machine, and long pipes require higher pressures plus golf requires even larger machines and sometimes multiple machines to purge the large and long piping systems and valve-in-head sprinklers.

3. Prior to opening the air valve on the air compressor, open an escape route for the water through an irrigation valve or a quick coupler (QC) so the mainline does not become overcharged. Remember air, not like water, is very compressible. If you let the air compressor charge up the mainline without expelling air through an opening, the mainline pipe burst pressure rating can be surpassed causing a mainline blowout. The other problem is when the sprinklers are cold and the plastic is hard and you open a station which has very compressed air, you most likely will end up sending the sprinkler heads to the moon.

4. The system can be automatically run from the controller with the water off and the air on, or each valve can be manually opened so that you know each zone is clear of water. If operating the system automatically remember the sensors may not let you start the system until they are bypassed.

5. Ensure that all water is discharged from the system. This is indicated when the surging water stops and only a fine mist is being discharged. This can take a few minutes to much longer depending on how much water is in the mainline.

6. Remove the tops off of the rain sensor and store inside the controller cabinet so that the top is in front of you at spring startup and can be put back so the system does not water during a rain event.

7. Only breaks that will allow water into the pipes are repaired at this time of year. No other work needs to be done at this time. It is best left for the spring startup.

8. Be certain to wire tie the water turn-on valve in the closed position. Even better is to use a crimp tag device like the city uses on the water meters. This way you can see if anyone has tampered with the water supply valves during the wintertime.

9. If a hose bib is your connection point, and the owner will use the hose bib after you have winterized the irrigation system, you must disconnect the irrigation mainline and plug it so water cannot enter the piping system.

10. Any drain that will not allow water to enter the system needs to be wired open. This will allow any water that seeps into the system to drain if it reaches the drain device.

Remember—water has a mind of its own. If you leave an opening, it will find it. Beware!

Lorne Haveruk, CLWM, CID, CIC, CLIA, CGIA, WCP, principal, DH Water Management, educator and author, is one of the country’s leading water resource consultants. DH Water is focused on all aspects of water resource management, educating those who manipulate water for outdoor uses. For educational offerings and other services, visit http://www.dhwatermgmt.com. This material is for information purposes and is not intended to provide legal advice. To contact the author directly, email lorne@dhwatermgmt.com.

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