Pipes Whistling or Squealing

What's happening?

A whistle is water going through a very narrow opening at speed. It comes from the opening, not from the long run of pipe, and it often changes pitch as the flow changes. The opening may be a valve that is part-closed, a tap washer that is dragging, a float valve whose seat has scaled, or a flow restrictor. A squeal can be a washer or a pipe rubbing as it expands. Where the sound first starts tells you the place: at a tap, at a cistern, at a valve by the boiler, or in the wall between. A steady, deeper hum is the humming or vibrating page; a bang is the banging pipes page.

What usually causes it?

• A stop tap or isolating valve left partly closed
• A worn or loose tap washer that chatters under flow
• A cistern float valve whose seat is scaled or worn
• A flow regulator or aerator clogged with scale
• A pressure-reducing valve that is whistling at high flow
• A pipe passing through a tight hole that squeaks as it moves with temperature
• A kinked flexible hose under a sink or toilet

Is it dangerous?

No. It is annoying and can point to a valve that is wearing. A whistle that becomes a leak at a washer or seal is the thing to catch early.

Can I fix it myself?

Run each tap and flush the toilet in turn to find which outlet starts the whistle. Check its isolating valve is fully open. Unscrew the aerator on a noisy tap and rinse the scale out. For a cistern whistle, shut the supply and clean or replace the float valve washer. If the sound follows the stop tap, open it fully and back a quarter turn. WaterSafe describes airlocks and noises in pipes, which can account for gurgling and uneven noises. If you cannot find the outlet, note when it happens and tell a plumber.

When should you call a plumber?

Call a plumber when you cannot trace the noise to an outlet, when it comes from a pressure-reducing valve or the stop tap, when new parts do not stop it, or when it is accompanied by leaks or a pressure drop.

What will the plumber actually do?

• Listen and test outlet by outlet to find the restriction
• Replace tap washers, cartridges, float valves and clogged aerators
• Open, replace or re-seat a stiff or part-closed isolating valve
• Check and adjust or replace a pressure-reducing valve
• Re-clip and sleeve pipes that squeak through walls or joists

Who fixes this

• Leak repair
• Tap and shower repair

What it usually costs

Leaking Pipe Repair Cost

£100–£500 for an emergency burst pipe

Questions people ask

Sources & References

1. WaterSafe: how to remove an airlock from water pipes
2. WaterSafe: banging noise from my pipework
3. WaterSafe: why is my water pressure low