What's causing that banging or gurgling noise in my pipes?

A single sharp bang when a tap or valve shuts

This is classic water hammer, caused by a sudden stop in fast-moving water sending a shockwave through the pipework, which can slam against joists or brackets. It's often worse on mains-fed systems with high water pressure, or where pipes aren't clipped securely. A washing machine or a solenoid valve closing quickly is a very common trigger.

Ticking or clicking as the heating warms up or cools down

Metal pipework expands as it heats and contracts as it cools, and if a pipe is running through a tight joist hole or plastic clip without room to move, that expansion produces a ticking or clicking sound, often traceable to one specific stretch of pipe under a floor.

A rumbling or kettling sound from the boiler

This is scale or sludge baked onto the heat exchanger, restricting water flow through it and causing localised boiling, which produces a sound very like a kettle coming to the boil. It's more common in hard water areas and in older systems without a working inhibitor. It shouldn't be ignored, since it puts extra stress on the heat exchanger.

Gurgling from radiators or pipework

Gurgling is almost always trapped air moving through the system as water tries to circulate around it, and it's usually solved with the bleeding routine covered in our radiator bleeding guide. If gurgling keeps returning within days of bleeding, suspect either a slow leak letting air back in, or the pump running faster than needed and disturbing air pockets before they can settle at the highest point.

A constant trickling or running water sound

If this is coming from near a cold water tank in the loft, or from an overflow pipe outside, it usually means a ball valve isn't shutting off properly, letting the tank overfill and trickle away through the overflow. On a sealed system, a similar sound near the boiler can indicate the pressure relief valve discharging, which needs looking at promptly.

Loose fixings and vibration

Sometimes noise is simply a pipe clip that's worked loose or gone missing over the years, letting a length of pipe vibrate against a joist or wall whenever water flows through it. This is one of the few pipe noises safely fixed with nothing more than a new clip and a few minutes' work, provided the pipe is accessible.

Quarter turn taps and water hammer

Modern quarter turn taps and single lever mixers close far faster than the old-style rising spindle taps they replaced, which is exactly why water hammer has become more noticeable in many homes over the years even though nothing else has changed. Where an old tap needed several turns to shut, giving the moving water time to slow gradually, a quarter turn tap stops the flow almost instantly, sending a pressure shockwave back through the pipe.

If hammer coincides with fitting new taps or a new washing machine, that timing is a strong clue, and a water hammer arrestor fitted close to the offending appliance often resolves it without any wider work to the pipework.

Pipe clip spacing and expansion in floor voids

Copper and plastic pipework both need clips at fairly regular intervals, typically no more than around a metre apart on horizontal copper runs, both to support the pipe's weight and to stop it swinging or knocking against joists as it expands and contracts with temperature changes. In older houses it's common to find clips missing entirely along a stretch of pipe in a floor void, often because access was needed for other work and the clip was never refitted.

Where a pipe passes through a joist, the hole should be a touch larger than the pipe itself, ideally with a piece of foam or pipe insulation sleeved around it, so the pipe has room to move slightly rather than binding tightly against bare timber every time it heats up.

Kettling and limescale build-up

Kettling gets its name for good reason: scale deposits on the heat exchanger create small pockets where water boils locally even though the rest of the system is nowhere near boiling point, producing a rumbling or popping sound very similar to a kettle. This is more common in hard water areas, and in systems where the inhibitor has never been topped up or has been diluted by repeated draining and refilling.

Left unaddressed, kettling tends to get gradually louder and more frequent as scale continues to build, and it increases wear on the heat exchanger, so it's worth having it looked at rather than simply living with the noise.

Pump speed and cavitation

Circulation pumps usually have two or three speed settings, and a pump set faster than the system actually needs can cause cavitation, where tiny vapour bubbles form and collapse rapidly within the pump, producing a harsh, grinding or rattling noise distinct from the softer gurgle of trapped air. This is more likely on smaller systems with a pump left on its highest setting from installation, or after a pump replacement where the speed wasn't matched to the property.

Turning the pump down a setting, where accessible and the model allows it, sometimes resolves this immediately, though persistent cavitation noise is worth mentioning to an engineer at the next service in case there's an underlying flow restriction elsewhere in the system.

Feed and expansion cistern noises

Older open-vent heating systems, rather than modern sealed systems, top themselves up from a small feed and expansion cistern in the loft, separate from the main cold water storage tank. A hissing or rushing noise from this cistern usually points to a ball valve that isn't seating properly, letting water trickle in continuously, sometimes alongside water finding its way out through the overflow.

Bubbling or gurgling from this cistern when the heating is running can also indicate a vent pipe issue, where the system is pumping water back up the open vent rather than circulating it properly, which is worth flagging to an engineer since it can affect how well the whole system fills and heats.

Cold water storage overflow noises

Separate from the feed and expansion cistern, a main cold water storage tank in the loft can develop the same overflowing ball valve fault, and the tell-tale sign is often a trickling sound from an overflow pipe on an outside wall rather than any noise indoors. This isn't strictly a heating noise, but it's frequently confused with one since both sounds can be traced back to the loft.

A stuck or worn washer inside the ball valve is the most common cause, and while replacing a ball valve washer is within reach for a confident DIYer, isolating the correct supply first is essential, so it's worth asking for help if you're not sure which valve feeds which tank.

Noise to likely cause at a glance

Frequently asked questions

Is it dangerous to leave a kettling boiler running?

It won't fail immediately, but running a boiler with scale on the heat exchanger over a long period increases wear and the risk of a cracked heat exchanger, so it's worth getting it looked at rather than living with the noise.

Can I fix water hammer myself?

Sometimes fitting a water hammer arrestor near the noisy appliance helps, but persistent hammer, especially on mains pressure, often needs a plumber to check pressure levels and pipe fixing.

Why does the noise only happen at night?

Pipes ticking as they cool is more noticeable at night once the heating has switched off and the house is quiet, and mains pressure can also be higher overnight when fewer households are drawing water, which makes hammer more noticeable too.

Will bleeding radiators stop all pipe noise?

It will stop gurgling caused by trapped air, but it won't touch ticking from expansion, kettling from scale, or hammer from valves closing quickly, since those have entirely different causes.