How to Winterize Your Irrigation System in Texas

North Texas weather is unpredictable. A 75-degree Tuesday can drop to 22 degrees by Thursday night — and that’s exactly the kind of swing that destroys irrigation systems. Here’s how to protect yours.

Why Texas Irrigation Systems Are Vulnerable

Many homeowners assume Texas winters are too mild to worry about freeze damage. The February 2021 winter storm and the December 2022 freeze proved otherwise. Even in a normal Denton winter, temperatures dip below freezing 25–35 times between November and March.

The most vulnerable components:

• Backflow preventer — Usually above ground and the first thing to crack. Replacement runs $250–$500.
• Valve manifolds — Shallow-buried valves in Denton’s clay soil often sit in water-saturated ground, making freeze damage more likely
• Exposed PVC risers — Any above-ground PVC is at risk below 28°F
• Drip irrigation emitters — Residual water in drip lines freezes and splits tubing

Step-by-Step Winterization

Option 1: Professional Blow-Out (Recommended)

This is the standard method for Denton-area irrigation systems and what most pros recommend:

1. The technician connects a commercial air compressor (80–100 PSI, 20+ CFM) to the system
2. Each zone is blown out individually until no water mist is visible at the heads
3. The backflow preventer is drained and left in a 45-degree open position
4. The controller is set to “rain mode” or turned off (keeps programming intact)

Time: 30–60 minutes for a typical 6–8 zone system.

Option 2: Manual Drain (DIY)

If your system has manual drain valves at low points:

1. Shut off the water supply at the irrigation shutoff valve
2. Open all manual drain valves (usually located at the lowest points in each zone)
3. Open the test cocks on the backflow preventer
4. Run each zone for 30 seconds to release pressure
5. Leave drain valves open through winter

Limitation: Manual drains don’t remove all water. Lines that run uphill or have dips will retain water.

What It Costs

Prices reflect the Denton, TX area as of 2026.

Spending $60–$125 on a blow-out is a lot cheaper than the $500+ repair bill from one hard freeze.

The Backflow Preventer: Don’t Forget It

The backflow preventer is the most expensive single component in your irrigation system, and it sits above ground exposed to every freeze. After winterizing:

1. Drain it completely by opening both test cocks
2. Leave the shutoff handles at a 45-degree angle (half-open)
3. Install an insulated cover — especially important for Denton homes where the backflow is on the north side of the house

Spring Startup Checklist

When temps stabilize above freezing in March, don’t just flip the system back on:

1. Close all drain valves and test cocks
2. Turn the water supply on slowly — opening it fast can cause water hammer and crack fittings
3. Run each zone manually and inspect for broken heads, leaks, and misaligned spray patterns
4. Check your controller schedule — North Texas lawns need different watering in spring than summer
5. Verify your rain sensor is working (required by Texas law for systems installed after 2009)

Bottom Line

Winterizing your irrigation system is the single most cost-effective yard maintenance task you can do in fall. For most Denton homeowners with 6–8 zones, a professional blow-out takes under an hour and costs less than a single broken head replacement.