Quick Answer:
Small bursts of air from faucets after the system is refilled are common after winterization. Open the affected faucet fully to purge trapped air, test hot versus cold to narrow the source, and note whether it follows power or plumbing outages. If the spitting returns after purging or shows up across multiple fixtures or floors, have a plumber trace the cause.
Why This Happens
During winterization you either drained or isolated parts of the plumbing. When you turn water back on, pockets of air can get trapped in pipes, mixing with the flow and causing sputtering or spitting. Other triggers include water heater refills, brief service outages, and recent valve or backflow work that lets air into the line. If you recently had a backflow device installed, consider checking related service notes on Air spitting after backflow install for context.
Step-by-Step What to Do
1. Open the faucet fully to purge air
- Turn the problem faucet to full open (both handles if it’s a two-handle fixture) and let it run for a minute or two. Running full flow helps push pockets of air out faster than a half-open faucet.
- Do this one fixture at a time so you can watch which ones clear and which keep spitting.
2. Test hot-only vs cold-only
- Turn off one side and run the other. If spitting happens only on the hot side, the water heater or its refill may be involved. If it’s only on cold, it points toward the supply line or a recent service on the supply—see notes on Air only on cold water.
3. Note timing after outages or heater refills
- Record whether spitting appears right after a power outage, when the heater refills, or after the main was shut for maintenance. Those events commonly introduce air.
4. Check upstairs versus downstairs behavior
- Run fixtures on different floors. If only upstairs fixtures spit, the problem is likely in the branch serving that level. If it repeats across floors, the issue may be at the service line, main shutoff, or venting.
5. Repeat and observe
- If purging clears the air and it doesn’t return, you’ve likely removed the trapped pocket. If it returns or moves to other fixtures, document times and affected taps to give to a plumber.
What Not to Do
- Don’t keep cycling the main shutoff valve trying to “chase” the air — this can create pressure swings and cause more issues.
- Don’t start dismantling cartridges, cartridges, faucet internals, or supply valves unless you are trained; that can damage seals and create leaks.
- If air returns after purging or affects multiple floors, don’t try complex fixes yourself — let a plumber inspect venting and supply components.
When to Call a Professional
Call a plumber if any of these apply:
- The spitting returns after you purge the lines.
- Multiple fixtures or floors are affected.
- It follows a recent service event (meter, backflow, or main work) and you can’t isolate the source.
A qualified plumber can safely trace whether the issue is trapped air, a venting problem, supply-line work, or a water heater refill issue and make targeted repairs.
Safety Notes
- Be careful with hot water—run cold first to avoid scalds when testing hot vs cold.
- Know where your main shutoff is, but don’t cycle it repeatedly. If you must close it, do so gently and only once while checking for leaks.
- If you smell gas, see damp patches, or find a burst pipe, evacuate and call emergency services or a licensed plumber immediately.
Common Homeowner Questions
- Why did this start after winterization? Trapped air in refilled lines or work on valves/backflow devices often introduces pockets of air.
- Is this damaging to my plumbing? Occasional spitting is usually harmless; persistent or widespread spitting can stress fittings and should be inspected.
- Can I fix it myself? Try purging each faucet and testing hot vs cold; if it returns or affects multiple floors, call a plumber.
For more related articles, see the Air Spitting From Faucets hub.