Shower Pump Problems: Causes, Checks and Fixes
Common shower pump faults in UK homes: no flow, noise, pulsing or running on, what you can safely check and when to call a plumber.
A shower pump boosts flow from a gravity-fed hot and cold water system, turning a feeble dribble into a decent shower. When it misbehaves, the symptoms are easy to spot but the causes are less obvious. This guide covers the common faults, what you can safely check yourself, and where the job needs a professional.
What a shower pump does
On a tank-fed system, water reaches the shower by gravity. If the tank is not high enough above the shower, flow is weak. A pump increases pressure from the hot and cold supplies and delivers a stronger spray. It is installed on the supply pipes, often in an airing cupboard or loft.
Common symptoms and likely causes
| Symptom | Likely causes |
|---|---|
| No flow, pump silent | No power, tripped switch, blocked inlet filter, empty tank |
| Pump runs but little water | Air in the system, blocked inlet filter, closed valve |
| Pump runs on after shower off | Faulty flow switch, air lock, or a worn seal |
| Pulsing or surging | Air in the pump or a partial restriction |
| Loud noise or vibration | Pump loose on its mount, air, or a worn motor |
| Hot or cold only | Valves, mixer or non-return valve problem |
Safe checks you can do
Power
Make sure the fused spur is on and the isolator, if fitted, is switched on. Do not open the pump casing or work on wiring. That is for a qualified person.
Valves and supply
Check the isolation valves on the pipes feeding the pump are fully open. A part-closed valve starves the pump.
Tank levels
Check the cold tank in the loft has water and the supply is working. Hot water must also be available from the cylinder.
Air in the system
After draining the system or working on it, air can be trapped. Turn off the pump, run the shower on gravity for a while to purge air, then try again. Some pumps have a specific procedure in the instructions.
Filters
Some pumps have inlet filters which can clog. Isolate the pump first if you do this. Rinse the filter and refit.
Position and installation issues
Pumps should be fitted in the right place, in the right orientation, and often below the cylinder level so they receive a flooded inlet. A pump positioned wrongly can suck in air, run dry and fail early. Noise often travels through floors and pipes when it is fixed rigidly, so rubber mounts help.
Pumps are also regulated by water rules; certain types are not allowed on a mains supply. See water regulations in plain terms.
When not to DIY
- Anything involving the electrical connection or opening the casing.
- Replacing the pump unit, which needs pipe cutting and fittings.
- Systems with a combi boiler, where a pump is typically not needed, and any adjustments around the boiler must be handled by a Gas Safe registered engineer.
For weak showers in general, start with low water pressure causes. For approximate costs of plumbing visits, see how much a plumber costs.
Prolonging pump life
- Keep tanks clean and covered.
- Descale the showerhead, which reduces back pressure.
- Do not run the pump dry.
- Have noisy or failing pumps replaced before they burn out.
Worked example: pulsing in a tank-fed house
A household has a shower pump in the airing cupboard. The shower starts well, then pulses and the pump seems to work harder. Checking the basics shows the pump's isolation valve on the hot side is only half open after a previous repair. Fully opening it fixes the pulsing. Had the valves been fine, the next steps would have been the inlet filters and checking the cold tank. The key point: most pump complaints turn out to be supply or valve problems rather than a failed pump.
Fault finding at a glance
| Check | Why |
|---|---|
| Is hot water available at other taps? | The pump cannot create hot water |
| Is the cold tank supply working? | Empty tank, no flow |
| Are both pump isolation valves open? | Partly closed valves starve the pump |
| Is the pump fused spur on? | Basic power check |
| Has the shower been unused for a long time? | Air in the pump |
Special cases
- Power showers and pumps differ. Check which you have, as the faults and parts are not the same.
- Pumps in lofts. They may be exposed to cold. Keep them insulated, as set out in frozen and burst pipes.
- Rentals. Report a failed pump to the landlord, who is generally responsible for installed equipment.
- Flats. Noise can carry through floors, so rubber mounts and a neighbourly word help.
Replacing a pump: what to expect
A plumber will look at the pipework, tank heights, positioning and electrical supply, then recommend a pump rated for your system. Expect them to discuss flow, noise and where to mount it. Ask if the pump is suitable for a tank-fed system and what warranty the manufacturer provides.
Sensible habits
Run the shower regularly, clean the showerhead and have an electrician check the connection if you are unsure about the wiring.
Frequently asked questions
Can I fit a pump to a combi boiler?
Generally no. Combi systems are mains-fed, and mains-fed pumps are restricted. Speak to a qualified engineer.
How long does a shower pump last?
It varies with use, water quality and installation, but many last several years. A pump showing repeated faults may need replacing.
Why is my pump noisy?
Air, loose mounting, or a worn bearing are the usual causes. Check the mount first, then call a plumber.