How to Winterize Your Sprinkler System
Protect your irrigation investment from Arizona's occasional winter freezes with this comprehensive winterization guide. While Phoenix winters are mild, temperatures can drop below freezing in December and January, causing costly damage to unprotected systems.
Safety Warning
Compressed air can be dangerous. Always wear safety glasses and never exceed 80 PSI when blowing out irrigation lines. If you're uncomfortable working with compressed air, hire a professional for $75-150.
Tools Needed
- Air compressor (10+ CFM at 50 PSI)
- Adjustable wrench
- Screwdriver set
- Safety glasses
Supplies Needed
- Foam pipe insulation
- Backflow preventer cover
- Teflon tape
- Bungee cords
Step-by-Step Instructions
Step 1: Turn Off the Water Supply
Locate your main irrigation shut-off valve (usually near the water meter or in the garage) and turn it clockwise to completely shut off water flow to the system. This prevents water from entering the pipes during the winterization process.
Step 2: Drain the Backflow Preventer
Open the test cocks and petcocks on your backflow prevention device to allow water to drain out. Leave them open throughout winter to prevent freezing damage. If you have a pressure vacuum breaker, remove the bonnet and internals.
Step 3: Activate Each Zone Manually
Turn on your irrigation controller and manually run each zone for 1-2 minutes. This helps push remaining water out of the pipes and identifies any zones that need attention.
Step 4: Blow Out the System with Compressed Air
Connect an air compressor (minimum 10 CFM at 50 PSI) to the blow-out port or mainline. Starting with the zone farthest from the compressor, activate one zone at a time and blow air through until only mist comes out of the sprinkler heads (typically 2-3 minutes per zone). Never exceed 80 PSI to avoid damaging pipes.
Step 5: Drain the Pump and Filter
If you have a pump system, open the drain plug at the bottom of the pump and filter housing. Remove any debris from the filter basket and leave the drain plugs out for the winter.
Step 6: Insulate Above-Ground Components
Wrap exposed pipes, valves, and backflow preventers with foam insulation sleeves or pipe wrap. Cover the backflow preventer with an insulated bag or blanket secured with bungee cords.
Step 7: Set Controller to Rain Mode
Switch your irrigation controller to 'Rain' or 'Off' mode rather than unplugging it. This preserves your programming while preventing accidental watering. If you have a smart controller, enable winter mode in the app.
Pro Tips
- Timing matters: Winterize in late November before the first freeze (typically early December in Phoenix).
- Don't skip zones: Even zones you rarely use need winterization to prevent freeze damage.
- Rent vs. buy: If you don't own an air compressor, rent one from Home Depot for $40/day rather than buying.
- Document your work: Take photos of valve positions and connections before disassembly to make spring startup easier.
When to Call a Professional
While winterization is a manageable DIY project, consider hiring Arizona Irrigation Repair if:
- You don't have access to a suitable air compressor
- Your system has complex pump or well components
- You're unsure about your backflow preventer type
- You want peace of mind with professional warranty coverage