How to winterize a sprinkler system – 4 key steps irrigation experts recommend

Sprinkler systems are hugely helpful in keeping lawns healthy and looking pristine throughout the year. While irrigation becomes less important as part of winter lawn care, it's vital you plan some time to winterize your sprinkler system. 

A failure to switch off and drain sprinklers can see any water in the system expand in the winter frosts, potentially bursting pipes and causing leaks that may not be evident until you switch the system back on.

As well as knowing when to winterize a sprinkler system, it is important to understand the steps required in switching off and draining the system. Some set-ups may be simple to winterize and be a DIY project, while others may require professional help.

Do I need to winterize my sprinkler system? 

It is always important to switch off and prepare a sprinkler system as part of any fall gardening checklist. A failure to do so can potentially result in a large repair bill. We hear from irrigation experts about the steps to take and methods to winterize different sprinkler systems.

How to winterize a sprinkler system in 4 steps

It is important to shut down a sprinkler system a few weeks before the first frosts are predicted for your area or US hardiness zone. By completing all the necessary steps in good time before temperatures plummet, it means that all water can be drained from the system and any components protected. As water expands when it freezes, any remaining in pipes and sprinkler heads can burst the components, cause huge damage, and face you having to pay for expensive fixes. 

Now you know why and when you need to switch off a system, so next it is important to understand how to winterize an irrigation system. Allison Harrison, the co-owner of Goodbee Plumbing, highlights the four key steps to shutting down and protecting any sprinkler system for the winter.

1. Turn off the water supply: The main water supply to the sprinkler system should be turned off 
2. Drain the system: There are several methods to drain water from the pipes, including the manual drain method, the auto drain method, and the compressed air blow-out method. The last one is most effective but requires professional equipment and expertise 
3. Insulate: Protect above-ground components, such as backflow preventers and valves, by insulating them with foam insulating tape or insulation bags
4. Shut down controller: If your system has a timer or controller, switch it to the “off” or “rain mode” to save electricity and wear and tear 

As Allison mentioned, there are different methods available to drain the system. It is important to refer to the manufacturer’s instructions, as different types of sprinklers will require specific methods. 

Josh Mitchell, plumbing expert and owner of Plumbing Lab, explains how some systems will have ‘manual valves at the low points’ and these can be manually opened to let the water drain out. Others may have automatic drain valves that will open when the pressure drops. He says that, by turning off the mains water supply, the system pressure will reduce and these valves should automatically open.

When talking about the blow-out method, Josh adds: ‘This involves using compressed air to force any remaining water out of the system. It's the most effective method, especially for systems in regions with deep freeze. However, it's vital to ensure the right amount of pressure, as too much can damage your system. Typically, 50-80 psi is sufficient, depending on the type of pipes used.’

To blow out a sprinkler system, an air compressor is used to remove the excess water from the pipes and sprinkler heads. However, too much pressure can damage the pipes or even cause injury, with debris capable of flying out of the system. It is generally recommended to use professionals when this method is required, to avoid causing potential large-scale damage to your irrigation system.

Allison Harrison

Allison Harrison is the co-owner of Goodbee Plumbing, a plumbing company serving the greater New Orleans area.

Josh Mitchell

Josh Mitchell is a plumbing technician and the owner of plumbinglab.com. Having worked with numerous homeowners on their irrigation systems, he understands the importance of adequately preparing for the cold months.

FAQs

When planning your fall lawn care regime, it's a wise idea to put winterizing an irrigation system on that list along with the usual tasks of aerating the lawn, scarifying, and overseeding.