Winterizing Your Irrigation System

Why Winterization Matters

Every autumn, Northumberland County residents face a critical task: preparing their irrigation systems for winter. Our region's freeze-thaw cycles can be brutal on unprotected irrigation equipment. When water freezes, it expands by approximately 9%—generating enough force to crack PVC pipes, rupture valves, destroy backflow preventers, and split sprinkler heads.

A single winter without proper winterization can cause thousands of dollars in damage. The good news? Winterizing your system is straightforward when done correctly, and this guide will walk you through every step.

When to Winterize

Timing is crucial. Winterize too early, and your lawn and plants may suffer from inadequate late-season moisture. Wait too long, and an early freeze could damage your system.

General Guidelines for Northumberland County

• Monitor forecasts: Begin preparations when overnight lows approach 5°C consistently
• Typical timing: Mid to late October for most of Northumberland County
• Lake effect areas: Properties near Lake Ontario may winterize 1-2 weeks later due to moderated temperatures
• Inland areas: Higher elevations away from the lake may need earlier winterization

Watch for the first frost warning—this is your signal to act within the week. Once temperatures drop below -5°C, the risk of pipe damage becomes significant.

Blowing Out the Lines

The most critical step in winterization is removing all water from underground pipes. The only reliable method is using compressed air to "blow out" the lines.

Equipment Needed

• Air compressor (minimum 50 CFM for residential systems)
• Pressure regulator (essential—never exceed 50 PSI)
• Quick-connect fitting matching your system
• Safety glasses and hearing protection

Important: Most home air compressors lack the volume (CFM) needed for effective blowouts. Rental compressors or professional service are usually necessary.

Blowout Procedure

1. Shut off water supply: Close the main valve supplying your irrigation system
2. Drain the mainline: Open any drain valves on the supply line
3. Connect compressor: Attach to your system's blowout connection point
4. Set pressure: Regulate to 40-50 PSI maximum (higher pressure damages components)
5. Blow zone by zone: Activate each zone manually and blow until only mist emerges from heads (usually 2-3 minutes per zone)
6. Repeat: Cycle through all zones twice to ensure complete evacuation
7. Final blow: Run each zone once more briefly (30 seconds) to clear residual moisture

Safety Warnings

• Never exceed 50 PSI—high pressure can crack fittings and damage heads
• Always wear safety glasses—debris can fly from sprinkler heads
• Stay clear of sprinkler heads during blowout—moving parts can cause injury
• Don't stand over heads while air is flowing

Draining the Backflow Preventer

The backflow preventer is one of the most expensive components in your system and the most vulnerable to freeze damage. It must be completely drained.

Pressure Vacuum Breaker (PVB)

1. Close the two shut-off valves (one on each side of the device)
2. Open the test cocks (small valves) on the device—usually two
3. Open the drain valve or remove the plug at the bottom
4. Leave all valves in open position for winter

Reduced Pressure Zone (RPZ)

1. Close inlet and outlet shut-off valves
2. Open test cocks (usually four)
3. Remove relief valve cover to drain body
4. Leave in open position for winter

Double Check Valve Assembly (DCA)

1. Close inlet and outlet valves
2. Open all test cocks
3. Open drain valves if present

If your backflow preventer is in an unheated area, consider having it professionally removed and stored indoors for winter.

Above-Ground Components

Anything above ground level requires special attention:

Backflow Preventer Protection

• Drain completely as described above
• Wrap with insulating material (fiberglass pipe wrap or foam insulation)
• Cover with waterproof plastic bag secured with tape
• Consider insulated enclosure boxes for permanent protection

Valve Boxes

• Confirm all valves are in open position after blowout
• Clear debris from boxes
• Ensure lids fit properly to keep water out
• Place foam insulation or old towels over valves for extra protection

Hose Bibs and Outdoor Faucets

• Disconnect and drain all hoses
• Store hoses in garage or shed
• Close interior shut-off valves if present
• Open outdoor faucets to drain remaining water
• Install foam covers on hose bibs

Controllers and Sensors

• Turn controller to "off" or "rain mode" (keeps programming but prevents activation)
• Remove battery backup if present
• Consider removing rain/freeze sensors and storing indoors
• Protect above-ground controllers with weatherproof cover

Spring Reactivation Checklist

When warm weather returns, follow this checklist to safely restart your system:

Before Turning On Water

1. Inspect all visible components for damage
2. Check valve boxes for debris or animal activity
3. Ensure all manual drain valves are closed
4. Confirm backflow preventer valves are properly positioned
5. Replace any damaged sprinkler heads
6. Reinstall any components removed for winter

System Startup

1. Open main supply valve slowly—opening too quickly can cause water hammer damage
2. Listen for leaks as pressure builds
3. Check backflow preventer for leaks
4. Activate controller and run through each zone
5. Verify all heads pop up and retract properly
6. Check for leaks around heads and fittings
7. Adjust head direction and spray patterns as needed
8. Verify coverage is complete and even

Programming Updates

• Update watering schedule for spring conditions
• Adjust run times based on plant needs and weather
• Test rain sensor operation
• Set correct time and date after power loss

When to Call a Professional

While many homeowners successfully winterize their own systems, consider professional service if:

• You don't have access to adequate air compressor equipment
• Your system is complex (multiple zones, drip irrigation, etc.)
• You're uncomfortable working with compressed air
• Your backflow preventer is difficult to access or drain
• You have a commercial-grade or very large residential system
• You discover damaged components during inspection

Professional winterization in Northumberland County typically costs $100-250 for residential systems—a worthwhile investment compared to repairing freeze damage.

Common Winterization Mistakes

• Inadequate blowout: Not running zones long enough leaves water in low spots
• Too much pressure: Exceeding 50 PSI damages fittings and heads
• Missing zones: Forgetting to blow out drip zones or secondary areas
• Not draining backflow: This is the most commonly damaged component
• Waiting too long: Early freezes catch procrastinators every year
• DIY with wrong equipment: Shop compressors often lack CFM to clear lines