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Lawn LandscapingAdvanced DIY1–2 hours (with contractor)

How to Winterize Your Sprinkler System

Before freezing temperatures arrive in New Jersey, it’s critical to properly winterize your sprinkler system. Any water left inside irrigation lines can freeze, expand, and crack pipes, valves, and sprinkler heads—leading to costly repairs in the spring. The most important step in winterization is the blowout process, which uses compressed air to clear water from the system.

However, this step requires precision. Effective blowouts depend on the correct CFM (air volume) and PSI (pressure)—too little air leaves water behind, while too much pressure can damage system components like valves and diaphragms. Because of this balance, most homeowners are better off hiring a professional rather than attempting a DIY blowout with improper equipment.

Winterization goes beyond just clearing the lines. A complete service should also include shutting down and programming the controller, draining or insulating the backflow preventer, and protecting exposed components. The best time to winterize is before the first hard freeze, typically in late fall. Skipping this process can result in burst pipes, hidden leaks, and expensive system repairs when you restart in spring.

Step-by-Step Guide

1. Shut Off the Water Supply

  • Locate and close the irrigation shutoff valve

  • Prevents additional water from entering the system

  • First step before any winterization

2. Drain Remaining Water (If Applicable)

  • Open manual drain valves if your system has them

  • Remove as much standing water as possible

  • Helps reduce freeze risk

3. Turn Off the Controller

  • Set controller to “off” or “rain mode”

  • Prevents accidental system activation

  • Some systems allow seasonal programming adjustments

4. Protect the Backflow Preventer

  • Drain water from the backflow device

  • Insulate with covers or foam if exposed

  • Prevents cracking during freezing temperatures

5. Disconnect Hoses and Accessories

  • Remove hoses from outdoor spigots

  • Store sprinkler attachments indoors

  • Prevents damage from freezing water

6. Schedule a Professional Blowout

  • Ensure system is fully cleared using proper equipment

  • Typically done zone by zone

  • Critical for complete winterization

7. Inspect for Existing Damage

  • Look for leaks or worn components before winter

  • Address issues early

  • Prevents compounding problems in spring

 

Tools & Materials

Everything you'll need to complete this project.

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Air compressor (for blowout)

DIY blowout requires a minimum 20 CFM compressor—much larger than the typical homeowner compressor. If you don't have one, hiring a pro is cheaper than renting the right equipment.

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When to Call a Pro

For most homeowners, the blowout process should always be handled by a professional. Proper winterization requires commercial-grade air compressors and precise control of air pressure and volume. Hiring a professional ensures your system is fully cleared without damaging components. It’s especially important for larger or more complex systems, or if you’re unsure about your setup.

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Frequently Asked Questions

Why can’t I just blow out my sprinkler system myself?

Most homeowner air compressors don’t provide the correct balance of CFM and PSI, which can either leave water behind or damage the system.

What happens if I don’t winterize my system?

Water left in the lines can freeze, expand, and cause cracked pipes, broken valves, and costly repairs.

When should I winterize my sprinkler system in NJ?

Before the first hard freeze, typically in late fall (October–November).

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