How to Winterize Your Sprinkler System

Sprinkler head surrounded by fall leaves

A sprinkler system helps beautify your lawn and garden. But to keep that irrigation system running smooth a long time, you have to winterize it as the weather gets colder and colder in many parts of the country.  The winterization process consists of a blow-out method of ridding all the water from all the irrigation components. If it doesn’t happen, the water will freeze and cause damage to the underground pipes, pumps, sprinkler heads, valves and other parts of your system.

“Winterizing an irrigation system is important because it ensures that all of the water is out of the entire system, eliminating any opportunity for freeze damage,” says Russ Jundt, founder of Conserva Irrigation, headquartered in Richmond, Va.

In the borderline freeze states that may or may not drop below freezing temperatures, it is still beneficial to winterize your irrigation system. It helps protect the lawn sprinkler system so that if a cold front moves through, you can rest assured that damage leading to costly repairs will not occur, he adds.

“In the northern climates where freezing temperatures are the norm, it is imperative that you winterize your irrigation system,” Jundt explains. “If you choose not to, severe and critical damage to the system will occur and costly repairs will be necessary in order to resurrect the system.”

Russ Jundt
Russ Jundt, Conserva Irrigation

Do It Yourself or Hire a Company

You do have a choice on winterizing a sprinkler system. You can do a DIY, if you have the right equipment, or hire a professional company that does this all the time.

You can research how to do it yourself through many online resources and DIY videos. Not all irrigation systems are the same, according to the University of Minnesota Turfgrass Science Department. When your irrigation system was installed, its size and all of its irrigation components will determine what steps you take and in what order. The university emphasizes that turning the job over to a certified irrigation professional is the best and safest choice. If you already hire a landscape company, they may already offer this service in your contract.

When searching for an irrigation company to winterize your system, Jundt says, seek out companies that:

  • Hold professional accreditations from the Irrigation Association.
  • Back their service with a no-freeze damage warranty (or similar).
  • Are licensed (where mandated) and insured, Jundt says.
  • Offers seasonal packages that include summer services as well.

Traditionally, homeowners fall prey to “weekend warriors” or other non-professionals that are dragging around an air compressor and offering a low-cost service — much below the retail rate.  By doing so, they are voiding any warranties that their irrigation system may have at that time and/or not receiving a quality assurance program, Jundt states.

Homeowners may place their sprinkler systems in jeopardy by relying upon someone unfamiliar with their particular system. They may put too much air pressure into the irrigation system’s pipes and heads and cause damage. They may also not get all the remaining water out, which could cause freezing damage.

Turning Off the Water Supply

You need to begin the process of winterizing your sprinkler system by turning off the water supply to your system, according to the Colorado State University Extension. A stop-and-waste valve or drain of some type should have been installed between the water supply and the backflow device. You need to shut this off, too.

You might have to hunt for it. Possible locations include the basement, a crawlspace or a valve box underground. The original builder might have buried the stop-and-waste 5 feet down, so you may need a long key. Take care not to force this valve while opening or closing it.

If your irrigation system is attached to domestic water, it is required to have a backflow preventer, according to the extension service.

The sprinkler heads should remain up after you blow out the water, and compressed air continues to flow through your irrigation system. That signals you used the right size compressor.

Blow Out One Zone at a Time

A compressed-air blow-out of a sprinkler system in progress
A compressed-air blow-out of a sprinkler system in progress. Credit: Conserva Irrigation

If you usually only run one zone at a time when irrigating, the system should blow out the same way. By pushing its limits and you try to do more than one zone at a time, the additional fast pace of the air flow and added friction could actually melt the pipes as they heat up. Even if the pipe and fittings do not burst during this operation, it could damage them and reduce their usable life.

You do need to know how many gallons per minute (GPM) flow through each zone.

Jundt emphasizes that the dangers associated with winterizing an irrigation system on your own include putting your system at risk for freeze damage.

“This can be catastrophic, as all parts of the system are not conducive to freezing water,” he says. “Additionally, if the anti-syphon device is not properly winterized, the plumbing damage can lead to flooding the home.”

Homeowners should look at the price of hiring a professional as an insurance policy against major damage.  A contractor in good standing should offer some sort of guarantee and warranty for their winterization services.

“A company that knows that they will be opening your system in the spring most likely will take extra care of your system and perhaps even take notes for system repairs and enhancements,” he adds. “Conversely, a non-professional “weekend warrior” type person offering cheap blow-outs has no incentive to winterize your system properly.”

If something goes sideways, good luck next spring tracking them down — let alone holding them financially responsible.

How Much It Costs

The average cost to winterize your irrigation system depends upon the region of the United States and also the size of the irrigation system. For an eight zone system or less, a customer should expect to pay somewhere between $75 – $125 to winterize the system properly with a professional company, Jundt says.

If you decide to do it yourself, add the cost of renting a more powerful air compressor and air hose to your list. Professional contractors use commercial air compressors that deliver airflow amounts of 90 cfm to 180 cfm, allowing them to properly evacuate the water from the system, he adds. They also know how to reduce or regulate the pressure so that you don’t introduce too much or use too little.

How Long Winterizing Takes

Airflow, as measured in cubic feet per minute (cfm), is the name of the game with regards to how long it takes to winterize a system, Jundt explains. If done correctly, running the air through every zone for two minutes each should do the trick. With some book-ended time on either end for setup and take-down, a professional contractor can winterize an eight-zone system in less than 30 minutes.

A DIY homeowner, on the other hand, usually does not have access to and/or chooses not to rent a commercial air compressor and uses instead a small air tank compressor delivering 4 cfm.  The low flow of air combined with allowing the tank enough time to regenerate and build pressure can lead to winterization times of three hours or more for the same size system.

Other Types of Systems

There are some contractors or homeowners that have constructed their irrigation system with manual drain valves on the low end, allowing the water to drain out after each watering cycle, Jundt says.

“Because these systems drain large amounts of water each time the system is done watering, they do not align with Conserva’s core value of water conservation and therefore we do not maintain these systems,” he states.

For those interested in winterizing these systems, Conserva still highly recommends still using an air compressor, as segments of the system may have settled in the soil and created low spots where water gathers. That makes it susceptible to freeze damage.

Protect Outside Faucets, Hoses, Too

Frozen garden hose
It’s a bit too late to protect this frozen garden hose. Credit: Infogramation of New Orleans, CC 2.0

You should shut down all exterior faucets for the winter season from the water supply. Remove and drain all garden hoses attached to the exterior faucets so freeze damage does not occur at the hose bib.

Additionally, turn off the valves to these faucets. Leave the faucet itself in the open position. That breaks the air vacuum so water can fully drain. If the water shut-off valve has a bleeder valve or similar, open it to drain the remaining house-side of the water in the pipe.

This methodology allows for all water between the shut-off valve and the outside faucet to completely drain, reducing the chances of freeze damage. In the event that a frost-free faucet has been installed, there is no need to winterize them.

“However, if you do not plan to use these faucets in the winter season, it is still a best practice to follow the procedure as outlined above. In certain rare occasions, even frost-free faucets have frozen in extreme temperature drops.  It is better to be safe than sorry,” he says.

In his many years as an irrigation contractor, Jundt has witnessed several irrigation systems in which the homeowners did not handle the winterization properly with an air compressor or have it done at all.

“The damage typically is catastrophic, and the repair costs are into the thousands of dollars,” he says.

Lee Nelson

Lee Nelson

Lee Nelson, an experienced freelance writer and former award-winning newspaper reporter, writes for National Association of Realtors and many state Realtor magazines. She lives in Illinois with her high school sweetheart and loves cooking, swimming, traveling and spending time with her grandchildren.