Quick Answer:
Small bursts or spitting of air from faucets right after service is restored is usually trapped air in the pipes or the water heater refilling. Open the affected faucet fully to purge the air, test hot and cold separately, and watch whether it happens on multiple fixtures or floors. If it keeps coming back across several fixtures, have a plumber trace the supply and venting so the source can be found safely.
Why This Happens
- When water service is shut off and then turned back on, air enters the supply lines and becomes trapped. That air is expelled as sputtering or spitting when pressure equalizes.
- The water heater can also trap air while refilling after being drained or losing pressure; hot-side sputtering points to that location.
- Differences between upstairs and downstairs behavior often point to where the air is trapped or to separate supply branches.
- Occasionally a pressure-regulating device, a faulty check valve, or blocked venting can let pockets of air form or re-enter the system, especially if it repeats across multiple fixtures.
- For brief background reading on related startup behavior, see Air spits before water flows.
Step-by-Step What to Do
1. Open the faucet fully to purge air
Turn the problem faucet all the way on (full flow). Let it run until the sputtering stops and the stream is steady. This is the simplest and often fastest cure.
2. Test hot-only vs cold-only
Run the cold side only, then the hot side only. If sputtering shows up only on hot, the water heater refill or an internal heater valve is likely involved. If only on cold, the street supply or a cold-side fitting is more likely at fault.
3. Note timing: after outages or heater refills
Ask whether the sputtering started right after a known outage, municipal work, or after the heater was drained/refilled. That timing helps narrow whether the issue is trapped air from the service or the heater.
4. Check upstairs vs downstairs
Turn on fixtures on different floors. If upstairs fixtures sputter and downstairs do not (or vice versa), the trapped air may be localized to that branch. This distinction helps a plumber target the right section of piping.
5. Purge multiple fixtures if needed
If one faucet is clear but another still spits, open all faucets (including tubs and outdoor spigots) and flush each until steady. Flush low points like laundry tubs and hoses last to clear any remaining pockets.
6. If you see it again, document details
Note which faucets, whether hot or cold, when it started, and whether it followed an outage or heater work. Photos or short notes will help a plumber diagnose if the problem is persistent.
For a common pattern where air shows up across fixtures after an outage, you may find useful guidance under Air in faucet after outage.
What Not to Do
- Don’t keep cycling the main valve or dismantling cartridges; if air returns after purging or affects multiple floors, let a plumber inspect venting and supply components.
- Don’t use tools to force apart fixtures or cartridges unless you know the exact part and how to reassemble — that can cause leaks or permanent damage.
- Don’t assume it’s a gas leak or appliance failure; air in pipes is common after service work and usually harmless when identified correctly.
When to Call a Professional
- When sputtering returns after you purge multiple fixtures or affects several floors — it may indicate a failing check valve, pressure regulator, or trapped air in a closed loop.
- If you can’t narrow it to hot or cold, or if the water pressure is unusually low along with the spitting.
- If you notice other signs like banging noises, continual pressure drops, or water discoloration — these may need diagnostic equipment and a qualified plumber to trace the source safely.
Safety Notes
- Be cautious when testing the hot side — water can be scalding. Start with low flow when first turning hot on.
- Shutting off the main supply can stop flow quickly, but don’t cycle it repeatedly; do one controlled shut-off if needed and reopen slowly to minimize air entry.
- If you suspect a major pressure problem or a damaged valve, stop and call a professional to avoid sudden bursts or flooding.
Common Homeowner Questions
- Why did this start suddenly? Brief answer: Most often because the supply was shut off and then restored, or the heater refilled; trapped air moves into faucets when pressure changes.
- Can I fix it myself? Brief answer: Often yes — purging by running faucets and flushing lines will clear trapped air. Call a plumber if it returns across multiple fixtures or floors.
- Is it dangerous? Brief answer: Not usually, but watch for scalding on the hot side and call a pro if pressure problems or leaks appear.
For more related articles, see the Air Spitting From Faucets hub.