How to Blow Out Sprinklers for Winter


Winterizing your sprinkler system by blowing out sprinkler lines is an essential annual maintenance task in colder climates. Allowing water to freeze inside pipes and sprinkler heads can lead to costly bursts and repairs come spring. Properly blowing out sprinkler systems removes residual water from lines and prevents freeze damage. With some basic knowledge and the right equipment, blowing out sprinklers is a straightforward DIY project for most homeowners. This guide will walk through the entire process of winterizing a sprinkler system by blowing it out. We’ll cover when to do it, what tools you need, how to drain and disconnect components, setting compressor PSI, and best practices for a successful winter sprinkler blowout. Follow these steps and tips for protecting your irrigation system from winter damage.

When to Blow Out Sprinkler Systems

The best time to winterize sprinklers by blowing them out is late fall just before the first hard freeze. This is often October or November for northern climates. Schedule your blowout around nighttime temperatures consistently at or below 32° Fahrenheit. Waiting too long increases the chance of overnight freezing with water still in pipes. Completing the process 1-2 weeks before the typical first freeze gives a good buffer.

Check long range weather forecasts a week ahead to pick an ideal blowout day. Choose a dry, sunny afternoon without rain or snow in the next 24 hours. Daytime warmth allows any lingering moisture to evaporate faster. Have your irrigation blowout completed before the first snowfall. Prioritize blowing out lines before shutting down an in-ground system from the water main.

Gather Necessary Blowout Equipment

Blowing out sprinklers requires an air compressor and some basic accessories. Many homeowners rent an air compressor powerful enough for the job. A minimum of 70 gallons per minute at 100 PSI capability is recommended for most residential systems. Commercial irrigation blowouts may need larger scale commercial air compressors. Here is the necessary equipment for a DIY sprinkler blowout:

  • Air compressor: Minimum 70 gallon, 100 PSI output is optimal.
  • Air hose: With a regulator, gauges, and quick connect fittings to attach to valves.
  • Drain key: Opens manual drains on irrigation valves.
  • Screwdriver: For opening valve boxes and accessing components.
  • Goggles: For eye protection when blowing lines out.
  • Ear protection: When working near loud compressor.
  • Blowout plugs: Insert into sprinkler heads to seal when blowing lines out.

Optional helpful gear includes a bucket to capture drain water and a camera for inspecting lines. Check that your compressor has adequate output size and pressure for the scope of your system. Ask at equipment rental centers for an appropriate sized compressor based on your irrigation system size.

Drain and Disconnect Components

Before using compressed air to blow out any lines, the system water supply must be shut off, drained, and disconnected. Start by closing the main shutoff valve from the irrigation system to the water supply. This is usually located near where the main irrigation line connects to the household plumbing.

Next open any manual drain valves on the main irrigation line and at zone valves. This drains the majority of water from the system so only compressed air will flow through. Unscrew the top filter housing on the main line to remove and clean out the filter.

Once water is drained, disconnect the irrigation system from the water supply. For in-ground systems, this usually means disconnecting a flex pipe fitting from the household plumbing main. Remove any backflow preventer devices and drain them fully. Disconnect backflow devices from supply lines.

Doing this drainage and disconnection prep ensures water is removed from the system before compressor air is introduced. Running an air compressor with water still in pipes can damage seals and internal components.

Set Compressor PSI Appropriately

Most residential irrigation systems utilize PVC pipes rated for pressure between 100 to 120 PSI before risk of bursting. Set your air compressor between 50 to 80 PSI for the blowout process. Monitor the pressure gauge occasionally and adjust the regulator to maintain this safe 50 to 80 PSI range.

If you have any thin walled poly pipe, set compressor PSI lower, from 40 to 60. Exceeding rated pressures can rupture pipes and fittings. Never leave a running compressor unattended during the blowout process. Pay attention to pressure gauges and regulator settings.

Also, limit compressor runs to 30 minutes before giving the machinery a cool down break to prevent overheating. The compressor should run steadily during each 30 minute cycle with no abrupt starts and stops which could spike pressures past safe levels.

Blow Out Each Zone Separately

To perform the blowout, you’ll move from one irrigation zone valve to the next, blowing each out individually. Start at the zone furthest from the water supply connection. This ensures no upstream water flows back into cleared out pipes.

Begin by removing the valve control box lid. Disconnect and remove any solenoid electrical wiring. Attach an air hose with quick connect fitting to the zone valve. Insert ear plugs and put on protective goggles before turning the compressor on.

Open the zone valve and let air flow at set PSI for 2 to 3 minutes initially. This blasts out the main pipes. Then insert blowout plugs into all the sprinkler heads on that zone. Turn the compressor back on so air flows through the sprinklers for another 1 to 2 minutes.

Listen for any hissing indicating leaks as you walk the zone. Finally, open any manual drain valves at the ends of pipes to release pressure. When flowing air peters out, that zone is fully winterized. Turn off the compressor before moving to the next valve.

Repeat this sequence for every irrigation zone until all have been blown out. Observe zone valves during the process for any leaks that could prevent building adequate line pressure. Turn off and drain any zones not getting sufficiently pressurized air.

Open Drain Caps at Low Points

Check your irrigation plans for any identified low point drains. These are caps placed at low sections of pipe where water could collect and freeze over winter. Low point drains are sometimes installed specifically for seasonal blowouts.

Use a drain key tool to remove any low point drain caps. Insert an adapter on your air hose and blow compressed air through the low point drains. Make use of these drains along with zone valves to ensure no moisture pockets remain. Secure caps once each low point is cleared.

Any areas where pipes dip below the frost line are candidates for potential freezing. Vigilantly blow out these low points and verify water is emptied from the system. Running air through for 5+ minutes creates a strong air purge “scrubbing” inside pipes.

Flush and Drain Main Shut Off Valve

Once all zones are cleared, open the main shut off valve still attached to the household plumbing line. Briefly turn on the water to flush residual interior water from the main valve. Then close the valve again and reopen all drains. This clears any standing water inside the valve body and prevents freeze damage to the valve itself.

Finish the process by fully disconnecting the main irrigation line from the water supply and draining any last water from the disconnected end. Check filters, backflow devices, and all maintenance components for remaining moisture. Leave valves, drains, and fittings open after completing the blowout.

Final Winterization Steps

With the full irrigation system now de-pressurized and empty of water, a few final winterization steps will help protect components:

  • Drain and store any above ground irrigation system hoses and accessories like sprinklers and soaker hoses. Disconnect timers, controllers, and shut off outdoor outlets.
  • Use a cover, towel, or burlap to insulate any outside section of PVC pipe from direct cold exposure and sunlight. Provide insulation for backflow devices if removing them entirely is not feasible.

-Secure valve box lids but leave the actual valves open and disconnected from water supply lines. Never close valves that have had water drained from the attached pipes as compressing air can damage seals.

  • Disconnect and drain any auxiliary pumps from ponds, wells, or other on-site water sources powering irrigation. Properly winterize pumps according to manufacturer directions.

Following a full irrigation system blowout, sprinklers and lines will be protected from freeze damage as temperatures drop. Just be sure to undo drain openings and follow proper spring start up procedures when gearing the system back up next growing season.

Frequently Asked Questions About Blowing Out Sprinklers

When should I have my sprinklers blown out?

Schedule your sprinkler blowout 1-2 weeks before the typical first freeze in your area, usually October or November. Have it completed before temperatures consistently reach 32°F overnight.

Can I blow out my own sprinklers?

Yes, with some simple equipment like an air compressor and accessories, homeowners can successfully DIY the blowout process following the steps outlined here.

How do you actually blow out sprinkler systems?

Shut off water, drain all lines, disconnect from supply, cap sprinklers, connect an air compressor to valves one zone at a time, and forcefully blow air through for several minutes per zone.

What PSI should you blow out sprinklers?

Most residential irrigation lines are rated for 100 PSI. Blow them out between 50-80 PSI to provide force while staying in a safe zone. Monitor pressure gauges when running the compressor.

How long does it take to blow out sprinklers?

Plan on about 30 minutes to 1 hour per zone for the full process of draining, disconnecting, blowing lines out, and depressurizing. Most residential systems take 2 to 5 hours total.

Do you have to disconnect backflow preventers?

Yes, remove and drain out any backflow prevention devices when blowing out sprinklers. Disconnect them from the main plumbing lines. Insulate external backflow parts if unable to remove entirely.

What can happen if you don’t blow out your sprinklers?

Frozen water left inside pipes and sprinkler bodies over winter can rupture and crack components. Only blowing out lines prevents this kind of freeze damage.

Should I insulate any sprinkler components for winter?

It’s smart to wrap any exposed sections of PVC pipe and backflow devices that remain outside over winter to insulate from frigid temperatures.

How soon can I turn water back on in spring?

Wait until overnight low temperatures are reliably above freezing before reconnecting and firing up your irrigation system in spring. Sudden cold snaps with water in lines again can still crack pipes.


Successfully winterizing your irrigation system by blowing out sprinkler lines takes some preparation and equipment but protects your system from catastrophic freeze damage. The process purges all water from pipes and components so compressed air remains over winter.

Follow the steps outlined here on the proper timing, gathering supplies, safely setting air pressure, disconnecting from main water, and methodically blowing out each zone and drain point. With proper PSI and procedure, this routine seasonal maintenance lets irrigation systems survive cold winters. Reach out to sprinkler installation pros as needed, especially for large or complex systems.

Taking time to properly blow out sprinklers can prevent thousands in repairs from cracked pipes, damaged valves, and burst heads. Make winter sprinkler blowouts an annual fall task for a trouble-free spring start up. Protect your irrigation investment and landscape all winter long with a thorough DIY or professional blowout.