How to Blow Out a Sprinkler System With Compressed Air (Safely)

Last updated: October 2026 · Written by the LawnVibe editorial team.

In cold climates, water left in sprinkler lines is a freeze risk, and drain valves alone often leave water trapped in low spots, valves and heads. A compressed-air blowout pushes that water out. Done carefully, it is the most thorough way to protect a system over winter. Done carelessly, it can crack pipes, damage heads and injure the operator. This guide explains how to blow out sprinkler system zones safely: the equipment you need, safe pressure, where to connect, the order to work in and the mistakes to avoid.

For the full winterizing process, including drain methods and backflow care, see our guide on how to winterize a sprinkler system.

When a blowout is needed

A blowout is the usual choice in cold climates when:

• The system has no manual or automatic drain valves.
• Drain valves exist but the layout leaves water in low spots.
• Heads, valves or laterals sit in places that do not drain naturally.
• You want the most thorough protection against freeze damage.

In mild climates with rare light frosts, a blowout may not be necessary; protecting the backflow device and exposed pipes is often enough. For timing, see our guide on when to stop watering and winterize.

How a blowout works

Compressed air enters the system below the backflow device and travels through the mainline, valves and laterals, pushing water ahead of it and out through the heads. Because air is compressible, it does not cushion pressure the way water does, which is why pressure control matters so much. Working one zone at a time, with the valve open before air is added, keeps air flowing through the lines and out of the heads rather than building up behind closed valves.

Equipment you need

The most common DIY problem is an undersized compressor. A small compressor can build pressure but cannot supply enough air volume to push water out of a zone, so water stays in the pipes. If your compressor runs constantly and heads only gurgle, rent a larger unit or hire a professional.

Safe pressure

Pressure is the setting that matters most for avoiding damage.

Air compresses and stores energy, so it behaves very differently from water in pipes. Excessive pressure can crack fittings, blow heads out of their bodies and damage valves. Set the compressor's regulator to a moderate pressure, start low and increase only if water is not clearing. Follow any guidance from your system's installer or manufacturer.

Before you start

Preparation makes the blowout faster and much safer. Gather everything below and walk the property first.

• Shut off the irrigation water supply.
• Drain the pipe between the shutoff and backflow device if possible.
• Set the controller so you can run zones manually, or use manual valve bleeds.
• Locate the blowout port, often a capped fitting or hose bib downstream of the backflow device. If there is none, an irrigation professional can add one.
• Mark heads and walk the zones so you know where air and water will come out.
• Wear eye and hearing protection, and keep people and pets away.

How to blow out sprinkler system zones step by step

Step 1: Connect the compressor below the backflow device

Check that the fitting is snug and rated for the pressure you will use. Attach the air hose to the blowout port or fitting downstream of the backflow device. Never push air through the backflow device, which can damage its internal parts.

Step 2: Close the backflow isolation valves

Close the backflow device's isolation valves as directed by its manufacturer so air goes only into the irrigation lines.

Step 3: Open one zone first

This rule protects both the system and you. Start a zone at the controller or open its valve manually before turning on air. Never pressurize the lines with all zones closed, which can build dangerous pressure and overheat valves.

Step 4: Start with the zone farthest from the compressor

Write down the zone order so you can repeat it on later passes. Many technicians begin with the zone farthest from the connection point or highest in elevation, then work toward the closest. This helps push water out of the mainline as you go.

Step 5: Introduce air gradually

Keep an eye on the pressure gauge throughout. Open the air valve slowly. Water will spray from the heads, followed by a mix of air and water, then mostly mist. Watch each head.

Step 6: Stop when only mist remains

Watch the farthest head on the zone, since it is usually the last to clear. When heads release only mist, close that zone and move on. Do not let air run through an empty zone for long; dry air moving fast creates friction and heat that can damage plastic parts.

Step 7: Repeat each zone in short cycles

Short repeated passes clear more water than one long one and keep parts cooler. Go through every zone, then repeat the whole sequence once or twice with short bursts. Water often collects in low spots after the first pass.

Step 8: Blow out drip zones carefully

Drip zones are low-pressure systems. Use very low air pressure, or simply open end caps and drain them instead.

Step 9: Disconnect and drain the backflow device

Let the compressor bleed down fully before touching any fittings. Once all zones are clear, turn off the compressor, release pressure from the hose, then disconnect. Open the backflow device's test cocks to drain it and set valve handles as the manufacturer directs. Insulate the device or remove it if designed to come off.

Step 10: Turn the controller off

This keeps the controller from opening valves on an empty system. Set it to off or rain mode for the winter.

Blowing out systems with drip zones and manifolds

Systems with several valve manifolds or a mix of spray, rotor and drip zones need a little more planning. Blow out spray and rotor zones first, then handle drip zones separately at very low pressure or by draining them through their end caps. Drip filters and pressure regulators are often best removed and stored indoors. If valves are spread across several boxes, open each box during the blowout to check for trapped water and leaks.

Hose bibs and other outdoor plumbing

A blowout protects the irrigation system, but other outdoor plumbing needs attention too. Disconnect hoses and hose-end timers, drain them and store them indoors. Shut off and drain outdoor faucets that are not frost-free. If you use rain barrels, drain them and disconnect them from downspouts before freezing weather.

Safety tips

Compressed air can cause serious injuries, so treat these as rules rather than suggestions.

• Never stand over heads, valves or fittings while air is flowing.
• Keep your face away from open pipes and blowout ports.
• Release pressure before disconnecting hoses.
• Do not exceed safe pressure for your pipes.
• Never run air with all zones closed.
• Keep children and pets indoors.

Common mistakes

Most blowout damage comes from a handful of avoidable errors.

• Using a compressor too small to move water.
• Pushing air through the backflow device.
• Using pressure that is too high for the pipe type.
• Letting air run through dry zones for long periods.
• Doing only one pass and leaving water in low spots.
• Forgetting drip zones and hose bibs.

Renting a compressor

If your home compressor is too small, rental shops often carry larger units suitable for sprinkler blowouts. When renting:

• Ask for a compressor rated for irrigation blowouts, with enough air volume for your system.
• Confirm the hose fittings match your blowout adapter, or rent the adapter too.
• Check that it has a working regulator and gauge.
• Plan transport, since larger compressors are heavy and some are towed.

How long a blowout takes

A typical residential system with several zones often takes under an hour once set up, including repeat passes. Larger systems, long laterals and systems with many low spots take longer. Most of the time goes into repeat cycles on each zone, which are worth doing.

Signs the blowout worked

• Heads release only mist, with no gurgling or spurts of water, on the final pass.
• Valve boxes are free of standing water from the lines.
• Drip lines run dry when end caps are opened.
• The backflow device has been drained and protected.

If you still see water on the final pass, run another short cycle on that zone.

After the blowout

Leave the controller off, keep the irrigation supply closed and make a note of the date and method. In spring, close test cocks and drains, open the supply slowly and check for freeze damage. Our guide on sprinkler freeze damage repair covers what to look for. If you are planning upgrades for next season, our roundup of the best in-ground sprinkler systems compares components.

When to hire a professional

Hire an irrigation professional if you lack a suitable compressor, have no blowout port, are unsure of your pipe types or simply prefer not to work with compressed air. Book early, since fall schedules fill quickly before the first freeze.

The EPA WaterSense program recommends seasonal irrigation maintenance, including proper winterization in cold climates.

The bottom line

To blow out sprinkler system zones safely, shut off the water, connect a compressor with enough air volume to a port below the backflow device, close the backflow isolation valves and always open a zone before introducing air. Use the lowest pressure that clears water, work zone by zone until only mist appears, repeat in short cycles and avoid running air through dry lines. Finish by draining and insulating the backflow device, and hire a professional if you lack the right equipment.

Frequently Asked Questions