Sprinkler winterization: what to know

What the job involves, what changes the price, and what to ask a pro.

What sprinkler winterization is

Sprinkler winterization clears water out of the sprinkler lines with compressed air before freezing weather, drains the valves and shuts off the supply so pipes and heads do not crack. People book it in the fall, once watering season ends, to protect the system from freeze damage over the winter.

Signs you need it

  • Freezing nights are coming and the system has not been drained for the season
  • Heads or valves were damaged by a freeze in an earlier winter
  • The backflow device sits above ground or in an area that can freeze
  • The controller and valves are exposed or in a spot that can get wet and cold
  • You do not plan to use the system through the winter and want it shut down properly

What the pro does

  • The technician shuts off the water supply to the system and checks the backflow device and the main shutoff
  • The controller is put in its off or rain setting, and the valves are checked for stuck or leaking parts
  • Each zone is run in turn, and the compressed air is set to a low, controlled pressure to blow water out of the lines
  • The backflow device and any drain valves are opened and drained so water cannot sit and freeze inside them
  • The technician checks the heads and valve boxes for water, and leaves a note on what was done and when the system should be started again

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Number of zones and the total length of the lines to be cleared
  • Whether the system has a backflow device that needs draining or insulation
  • Access to the valves, the backflow device and the main shutoff
  • Condition of the system, since leaks or stuck valves add time
  • Whether the controller is reset and checked during the visit
  • Whether repairs found during winterization are included or quoted separately
  • Whether a spring startup is booked at the same time

What a written quote should spell out

  • The number of zones blown out and the areas each one covers
  • Whether the backflow device is drained, insulated or protected
  • What is done to the controller and whether it is turned off or left on
  • What is checked for leaks, stuck valves or damaged heads, and what is repaired
  • Whether a spring startup is included or booked separately
  • The notes you will leave on the work done and the next steps

Questions to ask before you hire

  • How do you clear the lines, and what pressure do you use?
  • Do you drain the backflow device, and do you insulate it?
  • What do you do with the controller, and will it keep a schedule over the winter?
  • What do you check for leaks or damage when you run each zone?
  • Can you book the spring startup at the same time?
  • What happens if a line freezes anyway, and who fixes it?
  • Will you leave a note on the zones and the shutoff for next season?

Red flags

  • They do not shut off the supply before they start blowing out the lines
  • They blow out the lines at a high pressure that can damage the pipes and the heads
  • They skip the backflow device, or do not drain it, and say it is fine
  • They leave the controller powered and scheduled to run during freezing weather
  • They do not give you a note on what was done or when to start the system again

What you can do yourself

A homeowner can shut off the water supply, turn the controller to its off setting and drain any accessible drain valves on their own, following the system's manual. Compressed air work needs care with pressure and with the equipment, so call a licensed technician to blow out the lines unless you have the right training and gear. Keep people and pets clear of the valve boxes while air is being blown through the lines.

Licenses and permits

Sprinkler winterization may fall under irrigation contractor rules in some areas, and the backflow device may fall under separate rules. Check with your state or local licensing agency and your local water utility about the rules that apply to the work and to the device.

Sprinkler winterization questions

When should I winterize my sprinklers?

Book it before the first hard freeze in your area, since a freeze can crack the lines or the heads. Ask the technician to set the timing for your area, and to confirm the date on the schedule.

Do I need to winterize the backflow device?

Yes, if it is exposed to freezing temperatures or sits in a spot where water can collect. Ask the technician how they drain it and whether they insulate it, and check your local rules for the device.

Can I run my sprinklers in the winter?

Not in freezing weather, since water left in the lines can freeze and crack them. Keep the system off until the spring startup, and let the technician test it when you start it up again.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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