Quick Answer:

After a planned or accidental water shutoff, air can get trapped in the pipes. When you turn the water back on you may see sputtering or bursts of air and water from the tub spout. The usual fix is to purge the lines in a controlled way—open lower fixtures first, run cold then hot, let the pressure settle, and confirm normal flow returns. If noise or banging continues, stop and consider professional help.

Why This Happens

When water service is stopped, pipes can draw in air. That air moves around the system once supply returns, and it shows up as sputtering, gurgling, or short blasts at fixtures. The bathtub can be one of the last fixtures to clear because of long runs or higher elevation in the house. Small pockets of trapped air reduce flow and can make the fixture feel like it’s “spitting” rather than delivering steady water.

If the air moves quickly it usually clears on its own, but if it’s forced through at pressure you may also hear banging (water hammer) as valves and pipes take the shock.

Step-by-Step What to Do

1. Open lower fixtures first

Start with fixtures closest to where water enters the house or lower-level taps (basement sink, laundry tub, lower bathroom). Opening low fixtures first helps push air up and out toward higher fixtures like the bathtub instead of trapping it in low points.

2. Purge by running cold then hot

• Turn on the cold water at the lower fixtures first and let it run a minute or two until the flow steadies.
• Next open cold at the bathtub and let it run until sputtering stops or flow becomes steady.
• After cold is clear, repeat the same sequence with the hot water to purge any air in the hot lines. Hot lines can trap air separately if they run through a water heater or mixing valves.

3. Allow pressure to stabilize

Once you have run cold then hot at the fixtures, close them and wait a few minutes. This pause lets system pressure even out and any small remaining bubbles settle back into the flow rather than being forced through fixtures.

4. Listen for banging

Carefully listen while you run water again. A few clicks or short bangs are common as the system equalizes. Persistent loud banging that doesn’t fade when you reduce flow is a sign of water hammer or a pressure issue that needs attention.

5. Confirm normal flow returns

• Check that flow at the bathtub is steady and that the drain and hot/cold mixing work as expected.
• If normal flow returns and noises stop, the issue is resolved. If air returns or flow stays irregular, repeat the purge sequence once more, then consider calling a professional.

For more general guidance about how to clear air from water pipes, follow the same ordered steps and be patient as the system settles.

What Not to Do

• Do not rapidly turn the faucet on and off — that can worsen banging and create pressure shocks.
• Do not panic if it clears quickly — most air-related sputtering goes away after a brief purge.
• Do not ignore loud banging that continues — persistent water hammer can damage fittings and should be inspected.

When to Call a Professional

• Air and noise persist after two careful purge attempts.
• You hear continuous loud banging or clunking in the walls or pipes.
• There are leaks, visible pressure surges, or a dramatic drop in water pressure that doesn’t recover.
• If you suspect a problem with the water heater, pressure regulator, or check valves that could be causing trapped air or pressure spikes.

If you need a plumber, describe the steps you already took and mention persistent banging or repeated air pockets; that helps them diagnose quickly.

Safety Notes

• Avoid using excessive force on valves and handles; shutoffs can be old and brittle.
• Hot water can spray unexpectedly when purging hot lines—stand back and use care to avoid scalds.
• If you notice leaks, corrosion, or strange smells when water returns, stop and have a pro check the system.

Common Homeowner Questions

• Why did this only happen after the shutoff? Short answer: air entered the pipes while the system was depressurized and moved when supply resumed.
• Will repeating the purge fix it? Often yes; repeat the cold-then-hot sequence and allow pressure to stabilize between attempts.
• Could my water heater be involved? Yes—air can collect in hot lines or the tank. Purge hot taps and watch for irregular hot flow; call a pro if hot water problems persist.

If you still see your bathtub faucet spitting air after following these steps, pause and consider professional inspection—especially if noise or pressure problems continue.