DIY Sprinkler Blowout: Prep Your Lawn for Winter Like a Pro

Step-by-Step: How to Blow Out Your Sprinklers

Now we get to the actual work. Take your time with this process. Rushing through a blowout is how you damage components or miss a zone entirely.

Step 1: Turn Off Your Irrigation Water Supply

Locate your main water shutoff valve for the sprinkler system. This is usually in your basement, crawl space, or in a valve box near where your irrigation line branches off from your main water supply. Turn it completely off. Then open a manual drain valve if your system has one to release any initial pressure.

Step 2: Connect Your Air Compressor to the Blowout Port

Find your system's blowout port. It's typically a threaded connection near your backflow preventer or main valve assembly. Some systems have a quick-connect fitting, while others require you to remove a plug and screw in an adapter.

Attach your air compressor using the proper adapter fitting. Make sure all connections are hand-tight. You don't need to crank them down with a wrench because you'll be removing them multiple times.

Step 3: Open One Zone at a Time and Slowly Add Air Pressure

Here's where organization matters. Start with your controller or timer and activate the first zone. Don't turn on the compressor yet. Walk out and visually confirm which sprinkler heads pop up so you know you're working on the right zone.

Now go back to your compressor and slowly build up air pressure. Start around 50 PSI and gradually increase to 80 PSI for PVC systems or up to 100 PSI for polyethylene lines. Never exceed the manufacturer's recommended pressure.

Step 4: Run Each Zone Until Only Air Comes Out

Watch the sprinkler heads. At first, you'll see water sputtering out in bursts mixed with air. That's exactly what you want. Keep the air flowing. After 30 seconds to two minutes (depending on your zone size), you should see only a fine mist, then nothing but air.

When the heads are shooting pure air with no water droplets, that zone is clear. Shut off the controller for that zone but leave the compressor running for a few more seconds to get every last drop out.

Step 5: Disconnect and Repeat Until Every Zone is Dry

Move to the next zone and repeat the process. This is where marking your zones pays off. Use a different color flagging tape per zone to track your progress. I like to tie a piece of tape to each valve box cover after I've blown out that section. When I see six pieces of tape on six boxes, I know I'm done.

Don't rush between zones. Give yourself time to properly disconnect, reset the controller, and visually confirm the next zone before adding air pressure again.

Step 6: Insulate Exposed Backflow Preventers and Pipes

After all zones are clear, disconnect your compressor and close all valves. Now look for any exposed pipes or backflow preventers above ground. These need insulation. Wrap them with foam pipe insulation, old towels, or specialized backflow covers. Even though the water's out, metal components can still crack from extreme cold if they're not protected.

Common Mistakes to Avoid

I've watched enough DIYers make these mistakes that I need to warn you about them specifically.

Over-pressurizing the system: More air pressure doesn't mean better results. It means blown gaskets, cracked valve bodies, and sprinkler heads that shoot across your lawn like little plastic rockets. Stick to 80-100 PSI maximum. If you have older or more delicate components, start even lower at 60 PSI.

Skipping the backflow preventer: Your backflow preventer has internal valves and chambers that trap water. If you don't protect it, those valves will freeze and fail. The replacement cost? Anywhere from $150 to $500 depending on the model. Insulate it properly or drain it according to the manufacturer's instructions.

Not insulating exposed pipes: Just because the water's out doesn't mean the metal fittings and valve components can't crack from thermal stress. Any pipe above ground needs protection from freezing temperatures.

Color-coding your zones with Ace Supply's marking whiskers or flagging tape saves confusion and makes spring start-up easier too. When April rolls around and you're ready to reactivate your system, you'll know exactly which zone is which without playing a guessing game.

Bonus: Mark It Once, Save Time Every Season

Here's a pro tip that goes beyond just winter prep. Once you've gone through the effort of identifying all your valve boxes, sprinkler heads, and pipe runs, don't let that information disappear. Mark it semi-permanently.

Use durable marking flags to identify:

• Each valve box location

• The boundaries of each zone

• Any repair points or splice locations

• Spots where pipes run close to the surface (so you don't drive over them or plant a tree root on top of them)

I recommend leaving flags in place through winter. When spring comes and your grass starts growing, you'll know exactly where to look for valve boxes without probing around with a screwdriver. You'll know which zones to activate first for testing. You'll have a visual map of your entire system.

This isn't just about convenience. It's about protecting your investment. When you can quickly locate and access system components, you catch small problems before they become big ones. A leaking valve that you can find and fix in 20 minutes doesn't turn into a washed-out flower bed because you couldn't remember where the shutoff was.

Ace Supply's marking products are UV- and weather-resistant, built to survive a hard freeze and still stand tall come spring. They don't fade after one season, and they don't snap off in the first windstorm. That's the difference between marking supplies that work and ones that waste your time.

Frequently Asked Questions

How do I know if my sprinkler system needs to be blown out?

If you live anywhere that experiences freezing temperatures (32°F or below), your system needs a blowout. Period. Even one night below freezing with water in your lines can cause damage. Don't risk it.

What type of air compressor is best for sprinkler blowouts?

You need a compressor that can deliver sustained airflow at 80-100 PSI. Look for a unit rated at least 10 CFM (cubic feet per minute) at 90 PSI. Portable gas-powered compressors work great because you can position them near your blowout port.

How long should I run air through each sprinkler zone?

Run each zone for one to two minutes, or until you see only air coming from the sprinkler heads with no water droplets. Smaller zones clear faster. Zones with 10+ heads or long pipe runs may need the full two minutes.

Can I use a shop air compressor for this job?

Yes, if it meets the CFM and PSI requirements. Many shop compressors work fine for residential systems. Just check that your compressor can sustain 80 PSI with continuous airflow. Small pancake compressors usually don't have enough capacity.

What PSI should I use for PVC vs. polyethylene lines?

PVC systems should stay at or below 80 PSI because they're more rigid and prone to cracking under excessive pressure. Polyethylene (poly) pipe is more flexible and can handle up to 100 PSI safely. When in doubt, start lower and increase gradually.

How do I find the blowout port on my sprinkler system?

Look near your backflow preventer or main valve assembly. The blowout port is typically a threaded connection with a plug or cap. Some systems have it clearly labeled. Others hide it behind a valve box cover. Check your system's installation manual if you're struggling to locate it.

What happens if I skip one zone during the blowout?

That zone stays full of water, and when temperatures drop, you'll likely get frozen and cracked pipes in that section. Come spring, you'll see soggy spots, low pressure, or complete zone failure. Don't skip zones. Mark them off as you go to avoid missing one.

Can I blow out my sprinklers without an air compressor?

Not effectively. Some people try using a shop vacuum on reverse or even their car tire compressor. These don't provide nearly enough sustained airflow to clear an entire sprinkler system. You need a real compressor. Consider renting one if you don't own one.

Should I remove sprinkler heads before blowing out the system?

No. Leave them in place. They're designed to handle the air pressure, and removing them doesn't help the blowout process. In fact, it can make it harder because you're creating open holes that vent air before it pushes through the full length of pipe.

Is it safe to blow out the system if I have a backflow preventer?

Yes, but you need to follow the proper procedure. Most backflow preventers have test cocks (small valve ports) that need to be opened before blowing out the system. This prevents pressure buildup inside the backflow device. Consult your backflow preventer's manual for specific instructions.

How do I protect the backflow preventer from freezing?

After the blowout, insulate it with foam covers, old blankets, or specialized backflow insulation bags. Some backflow preventers have internal drain valves that you should open to let any remaining water out. The goal is to keep it from being exposed to sustained freezing temperatures.

How late in the fall can I safely do a sprinkler blowout?

Do it before your first hard freeze (temperatures at or below 28°F for several hours). In northern states, that might be October. In milder climates, you might have until late November. Check your local frost dates and plan to blow out your system at least a week before.

What signs show that all water has been cleared from the lines?

You'll see the spray pattern change from a solid stream to a sputtering mist, then to pure air. The sound changes too. Water makes a pulsing, gurgling noise. Air sounds steady and clean. When you see and hear only air for 30 seconds straight, that zone is clear.

How often should I replace my sprinkler fittings or hoses?

Inspect them annually. Replace fittings if you see cracks, corrosion, or leaks. Rubber hoses and gaskets should be replaced every 3-5 years or sooner if they show signs of dry rot or splitting. Don't wait for a failure. Preventive replacement is cheaper than water damage.

Do I need to disconnect my controller or timer after blowing out the system?

Most modern controllers have a rain mode or system off setting that stops the programming without losing your settings. Use that instead of unplugging it. However, if you have an older mechanical timer, you might want to turn it completely off to prevent accidental activation during winter.

How can I tell if I've used too much air pressure?

You'll hear loud banging noises in the pipes, or you'll see sprinkler heads shooting off their bodies. If fittings start leaking or you see water spraying from connections that were previously dry, you've exceeded safe pressure. Immediately reduce your compressor output and inspect for damage.

What's the best way to mark sprinkler heads for next spring?

Use small marking flags pushed into the ground next to each head. This prevents you from running over them with a mower or accidentally digging into them during spring landscaping. Flags are cheap insurance against costly repairs.

Wrap-Up: Keep Your System Safe, Organized, and Ready for Spring

Blowing out your sprinkler system isn't complicated, but it does require attention to detail and organization. Take the time to do it right. Work through each zone methodically. Mark your progress as you go. Protect exposed components from freezing.

This one afternoon of work protects the investment you've made in your irrigation system. It prevents spring surprises. It keeps your lawn healthy and your water bills reasonable because you're not paying for underground leaks.

Staying organized with marking supplies makes every season's maintenance faster and easier. When you can see where everything is, when you've color-coded your zones, when you've flagged potential problem areas, you're not just a homeowner. You're a pro DIYer who works smart.

Ready to tackle your next yard project with confidence? AceSupplyUSA.com has durable marking flags, tape, and mason line trusted by pros. They're perfect for organizing your sprinkler prep, planning new landscaping, or any outdoor project where knowing what's where saves you time and money. Check them out and see why contractors and serious DIYers rely on supplies that actually hold up to real-world conditions.