Tap Spluttering or Spitting Air
- How urgent
- Low risk
- Who fixes it
- A plumber
What's happening?
Taps spit because air that has collected in a pipe reaches the tap ahead of the water. After a mains shutdown, plumbing work or a drained tank, a few seconds of spluttering is normal. If it happens every day, air is entering the system or collecting at a high point. WaterSafe describes the signs as gurgling, uneven flow and sometimes banging. A tap that is only weak, without the coughing, is a pressure problem and sits on the low water pressure page. A hot tap that spits steam or boiling water is a different fault on a hot water system, not covered here.
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What usually causes it?
- The supply was shut off or drained and refilled for plumbing work
- A loft cold-water tank that ran low or empty, drawing air into the pipes
- A small leak on the suction side of the pipework letting air in
- A pipe run with a high point that traps air
- A faulty or partly closed isolating valve upstream of the tap
- A recent mains interruption, which clears itself after the supply returns
Is it dangerous?
No. The cost is a splashy tap, wasted water and a wet worktop. If the spitting is hot, do not hold your hand under the flow, because steam and hot water can arrive in a burst.
Can I fix it myself?
Run the affected tap fully open for a minute or two and let it clear. For a stubborn airlock, open the tap, then open a mains-fed cold tap, often the kitchen tap, and let the mains pressure push the air out. Starting at the lowest tap in the house and working upwards helps move air through. WaterSafe also describes joining the hot and cold taps with a hose to push air out. If it clears and comes back, check the loft tank level and look for damp around joints. Do not bleed radiators for a tap fault unless your system is showing a heating problem too.
When should you call a plumber?
Call a plumber when the spitting continues after the supply is back and the taps have been run, when it comes back daily, when the loft tank keeps running low, when you find a damp joint, or when a hot tap spits boiling water.
What will the plumber actually do?
- Establish whether the supply is mains or tank-fed and check the tank level and its float valve
- Clear the airlock with a hose or mains flow and bleed trapped air at high points
- Find and repair the leak or loose joint that lets air in
- Check isolating valves and any pump or accumulator upstream
- Re-test every outlet, hot and cold, for steady flow
Who fixes this
What it usually costs
- Leaking Pipe Repair Cost
- £100–£500 for an emergency burst pipe
Questions people ask
Why does my tap spit air and then run normally?
How do I clear an airlock from a tap?
Why does only my hot tap splutter?
Is a spluttering tap a sign of a leak?
Sources & References
Before you book, read what to check before a plumber starts.
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