Quick Answer:
If a faucet spits air after a new valve was installed, start by fully opening the affected faucet to purge air and test hot-only versus cold-only to narrow the cause. If the spitting is temporary and limited to one fixture it is often trapped air from the installation. If it repeats across fixtures, floors, or after outages, call a plumber so they can trace venting and supply components safely.
Why This Happens
When a valve is replaced or a section of supply is worked on, air can enter the piping. As water flows again the trapped air moves and comes out through taps as a sputter or small spit of air. Other common causes include a refilling water heater, a recent service outage, or a partially closed supply that lets air pockets form. If multiple fixtures or rooms show the same behavior, the issue may be higher up the system — venting, a pressure device, or a supply component — rather than just the one valve.
For similar situations, homeowners sometimes report problems like Air spurts when shower starts which can help show how air moves through fixtures.
Step-by-Step What to Do
1. Open the faucet fully to purge air
- Fully open the affected faucet (both hot and cold if it’s a mixer) and let it run for at least 2–3 minutes. This pushes trapped air out of the line.
- If you have an aerator on the faucet, remove it first to let air and sediment clear faster, then reinstall it after flushing.
2. Test hot-only vs cold-only
- Run hot water only, then cold water only. If only hot spits air, the water heater or its inlet may be introducing air during refill. If only cold does it, the problem is in the cold supply side or a recently worked valve.
- Testing separately helps identify whether the valve you installed affects one side or both.
3. Note timing: outages and heater refills
- Think back to whether the spitting started after a water outage, pressure event, or when the water heater refilled. Systems often draw in air during these events and then spit it when taps are opened.
- If spitting follows a heater refill, let the heater and lines purge fully by running hot water for several minutes at a lower fixture like a laundry tub before using upstairs fixtures.
4. Check upstairs versus downstairs behavior
- Test fixtures on different floors. If only upstairs fixtures spit air, the problem could be higher pressure or an upstairs branch trapping air. If both floors show the behavior, suspect a main feed or venting issue.
- Record which fixtures, which side (hot/cold), and how often it happens — this helps a plumber trace the source if needed.
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 apply excessive force to fixtures or plumbing joints to try to “shake out” air — you can damage fittings.
- Don’t use chemical additives or improvised tools inside fixtures to clear air pockets; these won’t solve a supply-side issue and can cause more problems.
When to Call a Professional
Call a licensed plumber if:
- Air returns after you purge the lines, or the spitting affects multiple fixtures or floors.
- There is a pressure drop, banging pipes, or persistent noise along with air spitting — these signs can point to venting or pressure-regulation problems.
- You installed the valve but are unsure if other supply components (backflow preventers, pressure-reducing valves) were disturbed — a plumber can test and trace safely.
If the situation seems tied to a recent backflow or device installation, a pro can check related parts; homeowners sometimes find more details in posts like Air spitting after backflow install.
Safety Notes
- Wear eye protection if you’re removing aerators or working at fixtures — spurts can spray water.
- Only shut off the main supply if you know where it is and how to safely restore it. If unsure, wait for help to avoid unintended pressure or fixture issues.
- If you smell gas, see major leaks, or encounter electrical hazards near plumbing, stop and call the appropriate emergency services.
Common Homeowner Questions
- Q: Will the air clear on its own? A: Often yes after thorough purging, but persistent or recurring air likely needs a plumber.
- Q: Can the water heater cause this? A: Yes — a heater refill or trapped air in the hot line commonly causes hot-only spitting.
- Q: Is this dangerous? A: No, air in the line is not dangerous by itself, but it can signal pressure or venting problems that need attention if persistent.
For more related articles, see the Air Spitting From Faucets hub.