Quick Answer:
If you see quick air spit or spurts when you first turn on the shower, it’s usually trapped air in the supply lines or a pressure change after an outage or service. Open the shower fully to purge the line and test hot-only and cold-only to narrow the source. If the problem repeats across multiple fixtures or after you purge, a plumber can trace the venting or supply components safely.
Why This Happens
- Water lines can trap pockets of air after meter work, repairs, or when a system is drained for work. Those pockets move and come out as spurts when a valve is opened.
- Pressure changes from municipal work or after power outages and water heater refills can let air enter the system or change how air is held in risers and branches.
- Localized issues (one fixture or one floor) point to a nearby valve, aerator, or fixture; repeated or house-wide spitting suggests a supply or venting issue a pro should trace.
- After specific events you may recognize patterns — for example, see **Air spitting after meter replacement** or **Air from faucet after long vacation** when a different cause is responsible.
Step-by-Step What to Do
1. Purge by opening the shower fully
- Turn the shower handle to the full open position and let water run for 30–60 seconds. This helps push trapped air out of the line.
- Repeat once more if you hear or feel another burst of air.
2. Test hot-only and cold-only
- Run cold only and note whether spitting occurs. Then run hot only. If it happens on one side only, the problem is likely on that supply line (hot side could point to the water heater or its valves).
- Use this to tell whether it’s a single-valve issue or a broader supply problem.
3. Note timing relative to outages or heater refills
- Ask whether it started after a power outage, after the water heater refilled, or after any work on the meter or main. Those events often let air into the system.
- If it began right after one of these events, simple purging often fixes it; if it keeps returning, it needs inspection.
4. Check upstairs vs downstairs behavior
- Run the same tests on fixtures upstairs and downstairs. If only upstairs is affected, the issue is likely in the upstairs riser or valves. If multiple levels are affected, the source is probably closer to the main supply.
- Make a short note of which fixtures spit and when — that helps a plumber trace the problem faster.
What Not to Do
- Don’t keep rapidly cycling the main shutoff valve. That can introduce more air and stress fittings.
- Don’t start dismantling cartridges, mixers, or trim pieces if you’re not comfortable — you can create leaks or damage seals.
- If air returns after purging, or the problem affects multiple floors, don’t try to chase it yourself: let a plumber inspect venting and supply components so the root cause is found safely.
When to Call a Professional
- If air spurting keeps happening after you purge lines and test hot vs cold.
- If multiple fixtures or floors are affected, or if the issue started after meter work, a prolonged outage, or repeated heater refills.
- If you notice pressure drops, banging pipes, or you can’t isolate whether the hot or cold side is involved — a plumber can trace supply lines, check vents, and test valves safely.
Safety Notes
- Be careful when testing the hot side — run it briefly at a hand-safe position first to avoid scalding.
- Wear eye protection if you’re working close to an aerator or shower head while purging, as small debris can be expelled with the air.
- Avoid turning off the main or removing parts under pressure; do not attempt work that requires shutting down the house supply unless you are confident and have proper tools and help.
Common Homeowner Questions
- Why did this start suddenly?
Often after meter work, outages, or heater refills; those events let air into lines. - Will it damage pipes or fixtures?
Occasional spurts usually don’t, but repeated pressure swings or air with debris can wear seals over time. - Can I fix it myself?
Try purging and the hot/cold test; if it keeps happening or affects many fixtures, call a plumber.
For more related articles, see the Air Spitting From Faucets hub.