How to Winterize Your Lawn Irrigation System (Without Guesswork or Frozen Pipes)
By Turfrain
To winterize your lawn irrigation system, shut off the water, drain valves and backflow, blow out lines with regulated compressed air, open and insulate exposed parts, and set your controller to winter mode. This prevents freeze damage, cracked heads, and costly spring repairs. Plan on a calm, dry day and follow safe pressure limits.
What you’ll learn from this blog
A fast, foolproof winterization checklist you can follow today
Safe compressor settings and how to avoid damaging pipes and heads
How to drain and protect your backflow preventer and valves
What to do with controllers, sensors, and drip lines
Answers to common “do I really need to blow it out?” questions
Start Here: The 20-Minute Quick Checklist
Think of this like putting your sprinklers to bed for the winter—fluffed pillows, lights out, door gently closed.
Shut off the irrigation water at the main isolation valve.
Relieve pressure: open a zone from the controller to bleed residual water.
Drain the backflow preventer: open test cocks and rotate ball valves 45 degrees so they’re half open.
Blow out zones with regulated air (see next section for safe settings).
Open low-point drains and end caps (especially on drip) to let gravity help.
Set controller to Off or Rain mode; save your schedule for spring.
Insulate exposed parts: backflow preventer, above-ground pipes, and valves.
Mark valve boxes and heads with flags if they sit low—so you don’t step on them during winter work.
Blowout Without Blowups: Air Settings, Flow, and a Calm Pace
If compressed air makes you nervous, you’re not alone. Done right, it’s gentle; done fast, it’s like trying to dry a sweater with a leaf blower—things stretch.
Equipment check: Use an air compressor with at least 5–10 CFM at 40–60 PSI and a proper adapter for your blowout port. More CFM clears water faster; high PSI isn’t the goal.
Safe pressures:
Spray/rotor zones: 40–50 PSI is plenty. Many pros top out at 50–60 PSI for large rotors, but staying on the lower side is kinder to parts.
Drip zones: Avoid high pressure. Open end caps or flush valves and let them drain; if you use air, keep it very low (10–20 PSI) or skip air and gravity-drain instead.
Method:
Start with the zone farthest from the compressor and work toward it.
Run each zone in short bursts of air (30–60 seconds), rest briefly, then repeat until only a fine mist comes out. Two to three passes per zone is common.
Keep one backflow test port slightly open during blowout to prevent trapping pressure.
Safety basics: Wear eye protection, stand back from heads as they purge, never exceed manufacturer limits, and don’t pressurize from the wrong side of the backflow preventer.
Handle With Care: Backflow Preventers and Valves (The Fragile Bits)
Your backflow preventer is the crown jewel—protect it, and everything else gets easier.
Shut off the irrigation supply, then open test cocks to drain. On a PVB (pressure vacuum breaker), tilt the ball valves to a 45-degree “half-open” position so water escapes and the body isn’t under stress.
Leave test cocks open over winter so trapped droplets can evaporate.
Wrap the backflow with an insulated cover or foam plus a weatherproof shell. If an Arctic blast is forecast, a towel under the cover isn’t overkill.
Valve boxes: pop the lids and check for standing water; sponge it out or improve drainage with gravel.
Your Controller, Sensors, and the “Do I Unplug It?” Question
Think of the controller as your system’s memory. You want it snoozing, not wiped clean.
Set to Off, Rain, or Winter mode so it won’t run zones during a warm spell.
Keep power on if it preserves your schedule and time; replace the backup battery if it has one.
Rain and soil sensors can stay in place; just confirm wires are snug and the sensor is not stuck or waterlogged.
A Real-Life Example: The “Almost Spring” Surprise
One homeowner skipped winterization because the fall stayed warm. A single January week of deep freeze cracked a rotor body and a 90-degree elbow. Come April, the first test run turned the lawn into a fountain show—and a $450 repair. A one-hour winterize in November would have prevented it. Lesson learned: don’t wait for frost to be obvious.
FAQ: Things Homeowners Ask Right Before the First Freeze
Do I need to blow out my sprinklers every year? In freezing climates, yes—especially with any above-ground or shallow piping. In mild zones, thorough draining may be enough, but blowing out is the safest bet.
When should I winterize? Aim for just before your area’s first hard freeze. As a rule of thumb, schedule when overnight lows consistently hit the low 30s°F or soil temps dip near 40°F.
What PSI should I use? Keep it conservative—around 40–50 PSI for most zones. The real mover is CFM (air volume), not raw pressure.
Can I damage my system with air? Yes, if you exceed pressure limits or blast drip lines. Regulate pressure, use short bursts, and follow manufacturer guidelines.
What about systems with automatic drains? They help, but water pockets still hide in laterals. A blowout clears those last sips that love to freeze and expand.
If You Only Do Three Things
Shut off water and drain the backflow preventer.
Blow out zones gently with regulated air.
Insulate exposed parts and set the controller to winter mode.
Wrap-Up and a Friendly Nudge
Winterizing your lawn irrigation system is a small, smart move that pays off big when spring rolls in. Shut off, drain, blow out gently, and protect the delicate bits—that’s the rhythm. If you’d rather have a pro handle it or want a pressure-perfect blowout, Turfrain is happy to help. Contact Us, and we’ll tuck your sprinklers in for the season.
