How to Turn On Your Irrigation System After Winter

TL;DR: Wait until nighttime temperatures stay above freezing, then slowly turn on your irrigation system, test each zone for damage, and address any leaks or broken components before regular watering begins.

When spring arrives in Western Washington, it’s time to wake your irrigation system from its winter sleep. But turning on an irrigation system after months of dormancy requires care. Rush the process and you risk burst pipes, blown fittings, or discovering damage only after water’s been flooding your yard for hours. When done properly, spring startup takes an hour and prevents costly problems.

When to Turn On Your System

Once nighttime temperatures stay consistently above 50°F with no frost in the forecast, you can safely start your system. In Whatcom County, this typically falls in late April to early May.

Check the soil, not just air temperature. Dig down 12 inches. If you hit frozen ground, wait another week or two. Frozen soil means water in your lines can still freeze, risking cracked pipes and fittings.

Monitor forecasts for late-season cold snaps. If temperatures are predicted to drop below freezing after you’ve started your system, shut it down until conditions stabilize.

Safety First: Important Warnings

Before you begin, understand these risks:

• Water hammer occurs when valves open too quickly. This shock wave can burst pipes or pop sprinkler heads off.
• Pressurized water can cause injury if components fail. Stand clear when first pressurizing the system.
• Electrical components require caution. Work with dry hands and follow the manufacturer’s instructions.

Disclaimer: This guide provides general information. You assume all risk. When in doubt, hire a professional.

Step-by-Step: How to Turn On Your Irrigation System

Step 1: Visual Inspection

Walk your property before turning on the water. Look for broken or shifted sprinkler heads, cracked valve boxes, exposed pipes, loose backflow preventer components, and signs of animal activity. Note any issues; you’ll test for hidden damage later.

Step 2: Locate Your Main Shutoff Valve

Find your irrigation system’s main shutoff valve in your basement, crawl space, or outdoor valve box. It’s typically a ball valve with a lever handle. When perpendicular to the pipe, it’s closed. Keep your controller set to off or manual mode.

Step 3: Prepare the Backflow Preventer

Your backflow preventer sits outside near the main valve. It has two large valves with handles and two small bleeder valves (test cocks). Close the small bleeder valves using a screwdriver, and turn them perpendicular to the valve body. Open the large valves by turning handles parallel to pipes. Replace any protective caps removed for winter.

If your system is older and doesn’t have a backflow preventer, North County can help by installing one. Backflow inspections are required annually, so contact us to get ahead of the game. 

Step 4: Turn On Water Slowly (Most Critical Step)

This step prevents water hammer damage. 

1. Open the main valve gradually, a quarter turn at a time.
2. Wait two to three minutes between turns.
3. Listen for pipes filling.

The entire process should take five to ten minutes minimum. Rushing sends a shock wave through your pipes that can crack fittings or burst pipes.

Step 5: Test Each Zone

Manually activate each zone from your controller, running each for three to five minutes. Watch for:

• Sputtering at startup (normal and should stop after 30 seconds)
• Geysers or fountains of water (broken underground pipes)
• Dry zones that won’t activate (valve failure or major break)
• Weak spray or mist (clogged heads or leaks)
• Heads spraying in the wrong direction (shifted during winter)
• Pooling water around valve boxes (leaking valves or fittings)

Take notes on problems to address after testing all zones.

Common Irrigation Damage in Western Washington

Our climate creates specific patterns of winter damage:

• Freeze damage: Cracked pipes, split fittings, broken backflow preventers from occasional hard freezes
• Soil heaving: Wet, heavy clay soils expand when frozen, which can push pipes and stress joints
• Clogged heads: Dirt, debris, and insects accumulate in sprinkler heads over winter
• Valve problems: Rubber diaphragms deteriorate, solenoids fail, or debris prevents proper closing
• Broken heads: Lawn mowers, foot traffic, or ground settling snap heads or pop them out of position
• Wire damage: Rodents chew through controller wires, which prevents zones from activating

When to Call a Professional

Some problems require professional help: underground leaks, backflow preventer damage, valve replacement needs, electrical issues, multiple broken zones, or systems not professionally winterized last fall.

Our irrigation repair and service handles these issues. For systems with extensive damage beyond economical repair, our irrigation installation services can design and install a new system.

Programming and Adjustments

Once your system tests are clear, reprogram your controller. Start with shorter run times than last summer; plants need less water in cool spring weather. Adjust as temperatures warm. Check heads regularly through the first few weeks. Small adjustments now prevent problems later.

Looking Ahead: Winterization Reminder

Proper winterization next fall prevents spring damage. Schedule winterization for mid-October through late November, before the first hard freeze. Professional compressed air blowout removes all water from lines, valves, and heads, protecting your investment and making spring startup straightforward.

Get Your System Running Right

Proper spring startup protects your irrigation system and ensures efficient watering through the growing season. Take it slow when opening valves, watch carefully during zone tests, and address problems before they worsen.

Found damage during startup? Contact us for irrigation service. We’ll diagnose issues, repair damage, and get your system watering.