Spring Sprinkler Start-Up: A Safe Step-by-Step Guide

Why it matters

Taking the time to properly reactivate your sprinkler system prevents "water hammer," a surge of pressure that can burst plastic pipes, crack valves, and destroy expensive backflow preventers. A controlled start-up also allows you to identify minor leaks or misaligned heads before they waste thousands of gallons of water or cause foundation damage.

By inspecting the system now, you ensure even water distribution, which prevents brown spots and reduces the need for expensive sod replacement or overseeding later in the summer. A well-maintained system can easily last 20 years, whereas a neglected one may require a complete overhaul in half that time.

How often

Sprinkler start-up is an annual task performed once the threat of a deep freeze has passed. Depending on your climate zone, this usually falls between March and early May. You should wait until the ground is no longer frozen at a depth of 6 inches to ensure the pipes can flex without cracking.

What you need

• Flathead screwdriver: For adjusting spray patterns and opening valve boxes.
• Small shovel or trowel: To clear dirt away from buried heads.
• Replacement nozzles/heads: (As needed) matched to your specific brand (e.g., Rain Bird, Hunter).
• Backflow preventer test cock key: (If your system requires it).
• Flag tape or small stakes: To mark broken heads for repair.

Step-by-step

Follow these steps in order to prevent internal pressure damage to your irrigation lines.

1. Check the soil

Before doing anything with the plumbing, ensure the frost is out of the ground. Dig a small hole about 6 inches deep in a sunny part of the yard. If the soil is still frozen or icy, wait. Forcing water into pipes surrounded by frozen earth can cause external pressure that leads to pipe failure.

2. Locate the main shut-off valve

Find the main irrigation shut-off valve, typically located in your basement, crawlspace, or a heated utility room near the main water line. Check that the "blow-out" caps (used during winterization) are tightly closed.

3. Inspect the backflow preventer

Go outside to your backflow preventer (the brass device usually located near the house).

• Close the two test cocks (small valves) using your screwdriver.
• Slowly open the shut-off valves on the backflow device.
• Crucial: If you see any cracks in the brass or if water sprays out of the body of the device, it likely froze over winter. Stop immediately and call a professional.

4. Pressurize the system slowly

This is the most critical step. Go back to the main indoor shut-off valve.

1. Do not flip the handle quickly.
2. Open the valve just a crack—about 1/4 turn. You should hear water rushing.
3. Wait until the sound of rushing water stops (this indicates the main line is full).
4. Gradually open the valve the rest of the way over the course of 1-2 minutes.

5. Manual zone test

Go to your irrigation controller (timer).

• Turn on Zone 1 manually.
• Walk the zone. Look for heads that don't pop up, heads that are leaking at the base, or "geysers" indicating a missing nozzle.
• Check for "bubbling" in the grass, which suggests a subsurface pipe leak.
• Clean any clogged nozzles with a small wire or replace them.
• Repeat this process for every zone.

6. Adjust and trim

While the zones are running:

• Straighten any heads that have tilted over the winter.
• Trim grass or clear mulch that is blocking the spray.
• Adjust the "arc" and "radius" of the spray using the adjustment screws on top of the heads to ensure you aren't watering the sidewalk or the side of your house.

7. Program the controller

Update the date and time on your controller. Check the backup battery (usually a 9V) and replace it if it's more than a year old. Set your watering schedule based on local spring restrictions, keeping in mind that spring usually requires significantly less water than July.

Safety

• Water Pressure: Always open valves slowly. High-speed water hitting a pocket of air (water hammer) can create pressure spikes exceeding 500 PSI, which is enough to explode PVC fittings.
• Electrical Hazards: Irrigation controllers are electrical devices. Ensure the outlet is GFCI-protected, and never handle the wiring with wet hands or while standing in water.
• Backflow Contamination: Never bypass the backflow preventer. It is the only thing keeping lawn chemicals and fertilizers out of your home’s drinking water.

When to call a pro

While most homeowners can handle a standard start-up, you should call an irrigation specialist if:

• The backflow preventer is leaking or shows visible cracks.
• You have a major underground leak (water pooling in the yard even when the system is off).
• Multiple zones fail to turn on (indicates a wiring or master valve issue).
• Your local municipality requires an annual certified backflow test (often mandatory).

Cost

• DIY: $0 - $50 (covers replacement nozzles, a few heads, or a new controller battery).
• Professional Start-up: $75 - $150 (depending on the number of zones).
• Backflow Testing: $50 - $125 (often a separate flat fee required by the city).
• Major Repairs: $200+ if the backflow preventer or main manifold was damaged by freezing.