Quick Answer:
Small bursts of air or “spitting” from a faucet after a repair are usually trapped air in the pipes or a refill of a water heater or main line. Open the affected faucet fully to purge air, test hot-only versus cold-only, and note whether it happens only after outages or meter work. If spitting repeats across multiple fixtures or floors, a plumber should trace the source safely.
Why This Happens
When a plumber works on water lines, replaces a meter, or the system is shut off for any reason, air can enter the pipes. That air becomes pockets that are pushed out when you open a faucet. Other common causes:
- Recent shutoff or service that refilled the supply lines.
- Water heater refilling after maintenance—hot lines can push trapped air to fixtures.
- Work at the meter or on the street that introduces air into the house supply.
- Pressure changes or a failing pressure-reducing valve or venting problem.
If this followed an outage, see the explanation in Air in faucet after outage. If it started right after utility work, it can also match issues seen with Air spitting after meter replacement.
Step-by-Step What to Do
Step 1 — Open the faucet fully to purge air
- Turn the affected faucet to full flow (both hot and cold if a mixing faucet) and let it run for 2–3 minutes. This often clears trapped air pockets.
- If you have multiple fixtures affected, start at the highest floor and work down to force air out of the system.
Step 2 — Test hot-only versus cold-only
- Run just the cold side and observe. Then run just the hot side and observe. If the spitting only happens on hot, the water heater or its refill may be involved. If only cold, the issue is likely in the supply side upstream of the heater.
Step 3 — Note timing and recent events
- Record whether spitting follows a power/water outage, a water heater refill, or recent repairs. That timing helps point to the source.
Step 4 — Check upstairs versus downstairs
- Compare fixtures on upper floors with those downstairs. If only upstairs fixtures spit air, the problem may be isolated to that branch or the riser. If it appears on multiple floors, the issue is more likely at the main supply, meter, or a system-wide component.
Step 5 — Observe for recurrence
- If the air clears and doesn’t come back, it was likely trapped air. If it returns after purging or continues across fixtures, stop and call a professional to trace venting and supply components.
What Not to Do
- Don’t keep cycling the main shutoff valve on and off—this can introduce more air and stress fittings.
- Don’t dismantle faucet cartridges or attempt deep repairs yourself unless you are experienced—cartridges and seals are delicate and you could cause leaks.
- Don’t ignore recurring problems. If air returns after purging or affects multiple floors, let a plumber inspect venting, the meter area, pressure-reducing valves, and supply components.
When to Call a Professional
- Air spitting persists after you purge the lines, or it keeps coming back.
- Multiple fixtures or floors are affected, indicating a system-wide issue.
- You notice pressure loss, noisy pipes, or visible leaks after the spitting starts.
- The problem began after meter replacement, major repairs, or if you suspect the pressure-reducing valve or venting is involved.
A plumber can safely trace the source with pressure tests and inspections without you having to guess or disassemble fixtures.
Safety Notes
- Be careful with hot water when testing—run hot-only checks briefly to avoid scalding.
- If you must shut off water for any reason, do so once and wait for the plumber if the issue is beyond a simple purge.
- Avoid makeshift fixes that require cutting pipes or using incorrect tools—call a pro for work on supply lines, the meter, or internal cartridges.
Common Homeowner Questions
- Why did this start after the repair? Brief: Repairs and shutoffs let air into lines; it usually clears when you purge the faucet.
- Is it dangerous? Brief: No—air in the pipes is not harmful, but repeated spitting or pressure loss needs a plumber to prevent damage.
- How long will it take to fix? Brief: If it’s just trapped air, purging takes minutes. If the source is a valve, meter, or venting issue, a plumber may need an hour or more to diagnose and fix it.
For more related articles, see the Air Spitting From Faucets hub.