Why is my shower pump noisy? Humming, vibration and cycling

Every shower pump makes some noise when it runs. A steady hum while the shower is on is normal. What is not normal is a pump that has become much louder, rattles the floor, screams, surges, or switches itself on when nobody is using water. This guide covers the usual causes on a gravity-fed system, the kind with a cold cistern in the loft and a hot water cylinder, which is what most domestic shower pumps are made for.

If you are still choosing a pump, see our shower pump sizing guide first.

What you can reasonably check

These checks need no tools beyond a torch and, for some, a screwdriver for an access panel. Follow the pump maker's instructions for your model. They describe what the householder may do and what will affect the guarantee.

Mounting and anti-vibration parts

Most pumps are supplied with anti-vibration feet and flexible hoses, so that the motor's vibration is not passed into the floor and the pipes. A lot of noise complaints come down to:

• the pump sitting directly on bare floorboards, or the feet having perished, been left off or been screwed down too tight;
• the pump touching a wall, a cylinder, a cupboard side or a pipe;
• rigid pipe connected straight to the pump instead of the flexible hoses;
• pipework near the pump not clipped, so it rattles when the pump starts.

The Bristan pump listings at Wickes, for example, mention anti-vibration feet, and the Salamander CT75Xtra listing says it includes anti-vibration hoses. Check that what came with your pump is fitted, and that nothing rigid is touching it.

A loose cover or panel

A loose plastic cover on the pump, or a cupboard door or panel near it, can buzz. With the pump isolated, check any external cover screws are in place, then try again.

Inlet strainers or filters

Many pumps have small strainers or filters on the inlets. If these block with debris or scale, the pump can starve of water, run rough and get noisy. The maker's instructions say whether the householder can clean them and how to isolate the water first. If they do not, ask a plumber.

Air in the system

Air trapped in the pipework or the pump can cause surging, spitting from the shower head and a rattling or grinding noise. It is common after the system has been drained, after the cold cistern ran low, or when a pipe run allows air to collect. The cure depends on the pipework. Some makers describe a simple venting procedure; persistent air usually points to the way the pipework or the hot water take-off from the cylinder was designed, which is a plumber's job.

Running dry

If the cold cistern in the loft is empty or very low, or a valve on the pump's supply is closed, the pump can run without enough water. That is noisy and can damage it. Switch it off and check:

• the cold cistern has water in it and the float valve is refilling it;
• any isolation valves on the pump's supply pipes are fully open.

If the cistern is empty because its float valve has failed, that needs fixing before the pump is used again.

It keeps starting on its own

Most pumps start when their flow switch detects water moving, or when a pressure switch detects a drop. The Bristan pump listings at Wickes, for example, say their flow switches start the pump once the flow from the shower or tap exceeds 0.8 litres per minute.

So a pump that starts briefly when nobody is showering is often reacting to something real:

• a tap on the pumped supply that is dripping or not fully closed;
• a leak on the pumped pipework;
• a toilet cistern or other fitting on the pumped supply refilling;
• a valve inside the shower that is letting water by.

Check every tap and fitting the pump serves. If nothing is obviously running, look for signs of a leak, and see our guide to finding a leak. If the pump still cycles with everything closed, it needs a plumber to look at the pump and its switch.

Undersized pipework or the wrong pump

A pump that has always been loud, surges, or cuts in and out under load may be on pipework that is too small for it, on a cistern or cylinder that cannot keep up, or simply the wrong type for the job. For example, a positive head pump in a position where there is little gravity flow can struggle to start reliably. A shower head that restricts flow heavily can also make a pump work against a near-closed outlet. These are design problems. A plumber can check the pipe sizes, the head of water and the pump type against the maker's instructions.

When to call someone

Call a plumber if:

• the noise continues with the pump properly mounted and the supplies open;
• you suspect air, a blocked strainer you cannot reach, or undersized pipework;
• the pump cycles with every tap closed;
• there is any leak at the pump or its hoses.

Call a qualified electrician if:

• the pump trips the electrics or blows its fuse;
• there is any sign of water near the electrical supply, or any burning smell;
• the isolating switch or fused spur is damaged.

A pump that is old and getting louder may simply be wearing out. Whether to repair or replace it is a judgement for a plumber, with the maker's guarantee terms in mind.

If you need a replacement pump

If a plumber says the pump needs replacing, use the sizing guide to choose the right type. These are two of the twin ended positive head pumps from that guide. Both are for gravity-fed systems only.

We haven't tested this. Figures are as the maker states them (checked 13 November 2026).

Is it normal for a shower pump to be loud?

A steady hum while the shower runs is normal. A rattle, a scream, a surge or a sudden increase in noise is not. Check the mounting and the supply first.

Why does my shower pump turn on by itself?

Usually because something on its supply is letting water through, such as a dripping tap, a refilling cistern or a leak. Check every fitting it serves before assuming the pump is faulty.

Can I fit a shower pump to a combi boiler to make it quieter or stronger?

No. Standard shower pumps are made for gravity-fed systems, not combis or unvented cylinders. See the low water pressure guide instead.