Sprinkler System Seasonal Care

An in-ground sprinkler system is a significant investment—typically $2,500-5,000 to install. It's also a system that's mostly buried and invisible, which means problems can develop without you noticing.

The two most critical times for your sprinkler system are spring startup and fall winterization. Get these right, and your system will run trouble-free for decades. Skip them, and you're risking cracked pipes, broken heads, and water bills that make you wince.

Task 1: Spring Startup#

After a winter of dormancy, your sprinkler system needs a careful restart. Turning everything on at once with full pressure is a recipe for blown fittings and damaged heads.

When to Start Up#

Wait until the danger of hard freezes has passed—typically late April to mid-May depending on your location. Check the extended forecast; you don't want to fill pipes only to have them freeze again.

Step-by-Step Startup#

Step 1: Inspect the System (Before Turning On)

Walk your property and look at each sprinkler head:

• Are any heads broken, tilted, or missing?
• Have any heads settled or been buried by soil?
• Is anything blocking the spray pattern (overgrown plants, debris)?

Check the backflow preventer and any above-ground components for visible damage from winter.

Step 2: Open the Main Valve Slowly

Locate your main water shutoff for the sprinkler system (usually near the backflow preventer or in a basement). Open it very slowly—take a full 60 seconds to go from closed to fully open.

This gradual pressurization prevents water hammer and reduces stress on fittings and heads. Turning on too fast is a common cause of springtime blowouts.

Warning: If you hear loud banging (water hammer) when opening the valve, close it immediately and open more slowly. Water hammer can damage pipes and fittings.

Step 3: Run Each Zone Manually

Go to your controller and run each zone manually, one at a time. While each zone runs, walk around and observe:

Check each head:

• Is it popping up fully?
• Is the spray pattern correct (not spraying sideways or misting)?
• Is water reaching intended areas?
• Any broken heads spraying straight up like a geyser?

Check for leaks:

• Pooling water around heads
• Soggy areas between heads (possible underground leak)
• Water bubbling up from the ground

Note any problems as you go. You'll fix them after you've surveyed the whole system.

Step 4: Check the Backflow Preventer

The backflow preventer keeps irrigation water (which may contain fertilizers, pesticides, or bacteria) from flowing back into your drinking water supply. It's usually a brass assembly with test ports above ground.

Look for:

• Leaks at any connection point
• Both shutoff valves in the open (handle parallel to pipe) position
• Frost damage (cracked body or fittings)

Backflow preventers should be tested annually by a certified professional—many municipalities require this.

Step 5: Adjust Heads and Fix Problems

Now address the issues you noted:

Tilted heads: Dig around the head and straighten the riser. Compact soil around it firmly.

Heads too low: Dig around and add soil underneath to raise them, or replace with a taller riser.

Wrong spray pattern: Adjust the arc and radius using the adjustment screw on the head (usually requires a flat screwdriver or special key).

Clogged heads: Remove the head, clean the filter screen, and flush debris from the riser.

Broken heads: Replace with the same type and model. Turn off water to that zone first.

Step 6: Program the Controller

Set your watering schedule for the season:

• Early morning watering (4-6 AM) is most efficient—less evaporation, less disease
• Water deeply but infrequently to encourage deep root growth
• Adjust for weather—reduce frequency during cool or rainy periods
• Check local watering restrictions—many areas limit watering days or times

Task 2: Mid-Season Check#

A monthly walk-through during the growing season catches problems early—before they waste hundreds of gallons of water or kill sections of your lawn.

What to Check#

Run each zone while watching:

• Heads pop up fully and retract completely
• Spray patterns haven't shifted
• No new broken or leaking heads
• Coverage is still reaching all intended areas

Look for signs of problems:

• Brown spots (not getting water)
• Overly soggy spots (too much water or leak)
• Grass growing over heads (may block popup)
• Mower damage to heads

Controller check:

• Battery backup is working (most controllers have a 9V backup)
• Schedule is still appropriate for current weather
• All zones are running according to program

Quick Adjustments#

Heads hitting sidewalks or driveways: Adjust the arc to stop wasting water on hardscape.

Grass blocking popup: Trim grass around heads or replace with taller heads.

Dry spots at edges: Adjust head spray radius or consider adding a head.

Task 3: Fall Winterization (Blowout)#

This is the most critical sprinkler maintenance task. Water left in pipes will freeze, expand, and crack pipes, fittings, and backflow preventers. Repairs typically cost $200-500+, and damage isn't visible until spring.

When to Winterize#

Before the first hard freeze—when overnight temperatures will drop below 32°F and stay there. In most northern climates, this means October or early November. Don't wait for the first freeze; schedule ahead.

The Blowout Method#

Most professional winterization uses compressed air to blow water out of all pipes and heads. This requires an air compressor capable of sufficient volume (not just pressure).

DIY vs. Professional:

Warning: Using too much pressure during blowout can damage heads, pipes, and valves. Maximum safe pressure is typically 50 PSI for PVC systems, 80 PSI for polyethylene. If you're unsure, hire a professional—the cost is far less than repairs.

DIY Winterization Steps#

If you have the right equipment and want to DIY:

Step 1: Shut Off Water Supply

Close the main irrigation water valve. Open the drain valve (if equipped) on the backflow preventer.

Step 2: Connect Compressor

Connect your air compressor to the blowout port. This is usually a threaded fitting on the backflow preventer or near the main valve.

Step 3: Set Pressure

Adjust the compressor regulator to appropriate pressure:

• PVC pipes: Maximum 50 PSI
• Polyethylene pipes: Maximum 80 PSI

When in doubt, use lower pressure—it just takes more time.

Step 4: Blow Out Each Zone

Activate one zone at your controller. Let the compressor blow air through until only mist (no solid water) comes from the heads—usually 2-3 minutes per zone.

Don't run the compressor continuously for more than 2-3 minutes per zone; you can overheat the pipes. Wait a minute between zones.

Move through all zones. Run each zone twice to ensure complete clearing.

Step 5: Shut Down Controller

Set the controller to "Rain" mode or turn it off. Remove backup batteries for winter or they may drain completely and leak.

Step 6: Drain the Backflow Preventer

Open the test ports on the backflow preventer with a flat screwdriver to drain remaining water. Leave them slightly open for winter (some people insert toothpicks to keep them cracked).

Turn the ball valves on the backflow to a 45-degree angle (half-open) so water can drain and won't be trapped.

What Happens If You Don't Winterize#

Skipping winterization in freezing climates is an expensive gamble:

• Cracked pipes: Underground pipes split and leak. You won't know until spring when you have a flooded yard and no water pressure.
• Broken backflow preventer: These cost $150-400 to replace, plus labor.
• Damaged valves: Zone valves crack and fail.
• Destroyed heads: Water freezing in heads cracks the bodies.

One year of skipped winterization can easily cost $500-1,000 in repairs. A professional blowout costs $50-100. It's not worth the risk.

Quick Reference: Sprinkler Maintenance Schedule#