How to Get Air Out of Hot Water Lines: A DIY Approach

You turn on the hot water and instead of a nice steady stream, the faucet spits, sputters, and makes a bunch of weird noises.

If that sounds familiar, there’s a good chance you have air trapped in your hot water lines.

The good news is that this is often a pretty simple problem to fix—especially if it started after a water shutoff, plumbing repair, or water heater replacement.

So, how do you get air out of hot water lines?

In many cases, all you need to do is open the hot water faucets and let the trapped air work its way out. But if the problem keeps coming back, there may be something else going on with your plumbing or water heater.

Here’s what to try first, what causes air in hot water pipes, and when it’s worth calling a plumber.

Why Is My Hot Water Faucet Sputtering?

A sputtering faucet is usually the first sign homeowners notice.

Instead of water flowing normally, you may get:

• Bursts of water followed by air
• Spitting or spraying from the faucet
• Hissing or gurgling sounds
• Water pressure that seems to jump around
• A faucet that briefly stops and then starts again

If it only happens for a short time after your water has been turned back on, it’s usually nothing to worry about.

Air got into the pipes while the system was drained, and now it needs somewhere to escape.

If it happens every day, though, that’s a different story.

How to Get Air Out of Hot Water Lines

Before assuming you have a major plumbing issue, try purging the air from the system.

Start With a Bathtub Faucet

If possible, start with a bathtub faucet.

Bathtub faucets usually move a lot of water and don’t have a small aerator on the end like a kitchen or bathroom sink faucet. That makes them a good place for trapped air to escape.

Turn the hot water on and let it run.

At first, you may hear some hissing and see the water sputter. That’s exactly what you’re trying to get rid of.

Keep it running until the water comes out in a smooth, steady stream.

Run the Other Hot Water Faucets

Next, go around the house and briefly run the hot water from your other fixtures.

Check:

• Kitchen sinks
• Bathroom sinks
• Showers
• Bathtubs
• Utility sinks

If you have a two-story home, make sure you check fixtures on both floors.

Once everything is flowing normally without sputtering, you’ve probably cleared the trapped air.

If One Faucet Is Still Acting Weird, Check the Aerator

Here’s a common situation: every faucet in the house is working normally except one.

That may not be air at all.

When water gets shut off and turned back on, small pieces of mineral buildup or debris can break loose inside the pipes. That debris can get caught in the little screen at the end of your faucet.

Unscrew the aerator, clean it out, and see if the water flow improves.

Why Does Air Get Into Hot Water Pipes in the First Place?

Air usually doesn’t just appear in your plumbing for no reason.

Most of the time, something happened recently that allowed air into the pipes.

You Recently Replaced Your Water Heater

This is one of the most common reasons.

When an old water heater is removed, the tank and at least part of the hot water system have to be drained.

When the new heater is filled, the water pushes the trapped air through the pipes and toward your faucets.

That’s why some sputtering right after a water heater installation can be completely normal.

If you’re having ongoing issues after an installation—or your current water heater is ready to be replaced—JLR Plumbing provides water heater installation in Spokane.

Your Water Was Shut Off

Maybe you had plumbing work done. Maybe the city shut the water off temporarily. Maybe someone closed the main water valve while working on a fixture.

Any time water drains out of your plumbing, air can take its place.

When the water gets turned back on, that air has to come back out somewhere.

Usually, your faucets are where it ends up.

Your Water Heater Was Drained or Flushed

If your water heater was recently drained for maintenance, repairs, or flushing, there will naturally be some air inside the tank and pipes afterward.

When the tank is refilled, opening a hot water faucet gives that air a place to escape.

Water heater manufacturers such as Bradford White commonly include this step as part of their filling and startup procedures.

You Had Plumbing Repairs Done

Replacing a faucet, repairing a pipe, installing a new fixture, or opening up a hot water line can all introduce air into the plumbing system.

If the sputtering started immediately after plumbing work, trapped air is one of the first things to suspect.

What If Air Is Only Coming From the Hot Water?

This is where things get more interesting.

If both your hot and cold faucets are sputtering, the issue may be somewhere in the home’s main water supply.

But if the cold water runs perfectly and only the hot water sputters, the water heater or hot water piping becomes a more likely suspect.

That doesn’t automatically mean your water heater is failing.

It could still be leftover air from a recent repair or installation.

But if you purge the system and the air keeps coming back, it’s worth having the water heater looked at.

JLR Plumbing offers water heater repair in Spokane for problems such as inconsistent hot water, unusual noises, poor hot water pressure, leaks, and other water heater issues.

Can Your Water Heater Actually Create Gas or Air?

In some cases, yes.

This is less common, but certain chemical reactions inside a water heater can create gas.

Your water heater has something called an anode rod. Its job is to sacrifice itself chemically so the steel tank doesn’t corrode as quickly.

Depending on your water chemistry and the type of anode rod installed, reactions inside the tank can sometimes produce gas.

That doesn’t mean every sputtering faucet is caused by an anode rod. Far from it.

But if air or gas repeatedly appears only on the hot water side, even after you’ve purged the system, it’s another reason to have the heater inspected rather than continually running the faucets and hoping it stops.

What If You Have Well Water?

If your home uses a private well, air in the plumbing can have a completely different cause.

Instead of the water heater, you might be dealing with something involving:

• The well pump
• Pressure tank
• Check valve
• Low well water levels
• Well piping
• Water treatment equipment

A helpful clue is whether the air shows up on both the hot and cold sides.

If every faucet in the house is sputtering, your water supply may be the better place to start troubleshooting.

Why Does the Air Keep Coming Back?

This is probably the biggest distinction between a minor nuisance and a plumbing problem.

If you recently had your water shut off and the faucet sputters for 30 seconds, then goes back to normal, there usually isn’t much to worry about.

But let’s say you purge the air today.

Tomorrow morning, the faucet is sputtering again.

You clear it.

Then it happens again the next day.

At that point, the question isn’t really how to get air out of your hot water lines anymore.

It’s why does air keep getting into them?

Recurring problems could point toward:

• A water heater issue
• Plumbing leaks
• Pressure problems
• A well system issue
• Water treatment equipment
• A problem that occurred during a recent repair
• Gas forming inside the water heater

That’s when it makes sense to stop chasing the symptom and figure out the actual cause.

Is It Actually Air—or Could It Be Sediment?

Water heaters can make some pretty strange noises, and homeowners sometimes assume they’re hearing air when the actual problem is sediment.

Minerals in the water can settle at the bottom of a tank-style water heater over time.

As sediment builds up, you may notice:

• Popping
• Crackling
• Rumbling
• Reduced hot water
• Inconsistent temperatures
• Poor hot water flow

If your faucet is sputtering and your water heater sounds like it has rocks bouncing around inside it, trapped air may not be the whole story.

A professional inspection can help determine whether the tank needs maintenance or whether something else is going on.

A Quick Warning About Electric Water Heaters

If you’ve drained an electric water heater, there’s one thing you definitely don’t want to do:

Don’t turn the power back on until the tank is completely full of water.

Electric water heater elements are designed to operate while submerged.

If you energize the heater while the tank is empty or only partially filled, the heating elements can burn out very quickly.

When refilling the tank, having a hot water faucet open allows air to escape. Once you get a steady stream of water without sputtering, the tank should be full—but you should still follow the manufacturer’s instructions for your specific water heater.

The U.S. Department of Energy also provides homeowner information about water heating and energy-efficient water heater operation.

How Long Should It Take to Get Air Out of the Lines?

There’s no exact number of minutes that applies to every home.

If only a little air entered the plumbing, it may clear almost immediately.

If your entire hot water system was drained, it may take longer.

Rather than watching the clock, watch the faucet.

You’re looking for:

Sputter, sputter, hiss…then a nice steady stream of water.

Once the water runs continuously without pockets of air, you’ve probably purged that section of plumbing.

When Should You Call a Plumber?

A little air after the water has been shut off isn’t usually a big deal.

But you may want to call a plumber if:

• The air keeps coming back
• Only your hot water lines are affected
• Your hot water pressure suddenly dropped
• The water heater is making loud noises
• Your water temperature keeps changing
• There’s water leaking around the heater
• Your hot water looks rusty or discolored
• You aren’t getting as much hot water as you used to
• The problem started for no obvious reason

Those additional symptoms can tell you a lot more about what’s happening than the sputtering faucet alone.

Need Help With a Water Heater Problem in Spokane?

If you were searching for how to get air out of hot water lines, start with the simple solution: run the hot water until the air clears and the flow becomes steady.

For a one-time pocket of trapped air, that may be all you need to do.

But if the sputtering keeps returning, don’t just keep purging the pipes. Something may be causing air or gas to continually enter the hot water system.

JLR Plumbing specializes in water heater repair in Spokane and can troubleshoot problems with tank and tankless water heaters, hot water pressure, temperature fluctuations, leaks, sediment buildup, and other hot water issues.

If your current heater is getting older or repair no longer makes sense, we also provide water heater installation and replacement in Spokane.

Serving Spokane, Spokane Valley, Cheney, Mead, Medical Lake, Airway Heights, and surrounding Spokane County communities.

Frequently Asked Questions

How do you get air out of hot water lines?

Turn on a high-flow hot water fixture, such as a bathtub faucet, and let it run until the sputtering and hissing stop. Then check the other hot water fixtures in your home and run them until the water flows normally.

Why is there suddenly air in my hot water lines?

Recent plumbing repairs, water heater replacement, water heater maintenance, or shutting off the home’s water supply can all introduce air into the plumbing.

Why is only my hot water sputtering?

If the cold water works normally but multiple hot water faucets sputter, the issue may be somewhere in the water heater or hot water piping.

Why does air keep coming back in my hot water?

Recurring air may indicate that something is continually introducing air or gas into the system. If you’ve already purged the plumbing and the problem keeps returning, it’s worth having the water heater and plumbing inspected.

Is it normal for faucets to sputter after replacing a water heater?

Yes. Some sputtering can be normal immediately after a water heater replacement because air enters the tank and plumbing while the system is drained. It should stop once the system has been completely refilled and purged.

Can sediment in a water heater cause sputtering?

Sediment doesn’t necessarily create trapped air, but it can cause popping, rumbling, pressure changes, and other symptoms that homeowners sometimes mistake for air in the plumbing.

Should I be worried about air in my water pipes?

A temporary pocket of air after plumbing work usually isn’t a major concern. Air that repeatedly returns, especially when accompanied by low pressure, leaks, unusual water heater noises, or inconsistent hot water, should be investigated.