Quick Answer:
If you see water spit with air after you adjusted the pressure-reducing valve (PRV), it’s usually trapped air being pushed out as the system rebalances rather than the house drawing air in. Open a nearby faucet fully to purge the line, test hot and cold separately, and watch whether the problem shows up on one floor or many. If the spitting keeps coming back across multiple fixtures or floors, call a plumber so they can trace vents and supply components safely.
Why This Happens
A PRV adjustment changes pressure quickly in the supply piping. That change can dislodge pockets of trapped air or cause dissolved air to come out of solution and spit through faucets. It is similar to what happens when water service is restored after work on the street; you may see short bursts as lines purge. If a water heater has been refilled or the home recently lost water, the heater can introduce extra air into the hot side and cause spitting specifically from hot taps.
Step-by-Step What to Do
1. Open a faucet fully to purge air
- Start at the lowest fixture near the PRV or where you first noticed the spitting. Open the faucet wide and let it run until all sputtering stops and the flow is steady.
- Run both a cold and hot tap for a minute afterward to be sure the line is clear.
2. Test hot-only versus cold-only
- Turn off the hot supply at a fixture and open the cold only; note whether spitting appears. Then do the reverse for the hot only.
- If spitting occurs only on the hot side, the water heater or its refill cycle is a likely source.
3. Note timing after outages or heater refills
- Record whether the spitting began right after a pressure change, a short outage, or after refilling the heater. Short-lived air bursts are common after those events and often settle with purging.
- For recurring events after service restoration, compare your experience to **Air bursts after water restored** for similar guidance from other cases.
4. Check upstairs vs downstairs behavior
- Test fixtures on different floors. If only upstairs fixtures spit, air pockets or venting on that branch may be the issue. If it happens across floors, the problem is more likely in a main supply, PRV, or shared component.
- If the issue recurs after purging and affects multiple floors, arrange for a plumber to inspect the building venting and supply components.
5. If you’ve had recent plumbing work
- After repairs or component replacements, run fixtures and check for spitting. Small amounts of air immediately after work are normal, but persistent spitting merits a pro inspection — see advice similar to **Air spitting after plumbing repair**.
What Not to Do
- Don’t keep cycling the main valve to “chase” the air. Repeatedly opening and closing the main can stress fittings and introduce more disturbance to the system.
- Don’t dismantle cartridges, valve internals, or the PRV yourself unless you are trained. These parts require proper tools and knowledge to avoid leaks or damage.
- If air returns after purging or affects multiple floors, don’t try more aggressive DIY fixes — let a plumber inspect venting and supply components.
When to Call a Professional
- The spitting continues after thorough purging of fixtures.
- Air affects multiple fixtures or multiple floors, suggesting a main-supply or venting issue.
- You see pressure drops, banging, or repeated loss of flow along with the air — these can indicate a failing PRV, check valve problems, or hidden leaks.
- You’re unsure where the air is entering, or the PRV needs adjustment or replacement. A plumber can pressure-test the system and trace the source safely.
Safety Notes
- Use steady, controlled steps: open a single faucet fully rather than rapidly changing multiple valves at once.
- If you shut off the main, know how to restore service and repressurize fixtures slowly to avoid surprise sprays.
- Avoid working on the PRV or water heater if you’re not qualified. Incorrect handling can cause leaks, scalding, or damage. Call a licensed plumber for equipment-level work.
Common Homeowner Questions
- Will the spitting stop on its own?
Often yes after you purge the lines; persistent or repeated spitting needs a plumber. - Is this damaging my pipes or fixtures?
Occasional air bursts are usually harmless; continuous air and pressure swings can stress fittings over time. - Can I adjust the PRV again to fix it?
Small adjustments may help, but repeated or large changes can cause more disturbance; have a plumber evaluate if problems continue.
For more related articles, see the Air Spitting From Faucets hub.