Shower pump not working: causes and what to check
A shower pump that will not start is usually down to one of four things: no power reaching it, not enough water reaching it from the cold tank or hot cylinder, a flow or pressure switch that is not sensing the tap being opened, or a motor that has seized or failed. What the pump does when you turn the shower on tells you which. Complete silence points to power or the switch. A hum without the pump spinning points to a seized motor. Starting and stopping, or running with a weak spray, points to air or a poor supply. If the pump is leaking or tripping the electrics, switch it off at its spur and leave it off until it has been looked at.
Loyal Plumbers · Updated
Discuss your plumbing workHow a shower pump works, and why it matters
Shower pumps are fitted to gravity-fed hot water systems: a cold water tank in the loft feeding a hot water cylinder, usually in an airing cupboard. The pump takes the low-pressure hot and cold water from those and boosts it to the shower. When you open the shower valve, water starts to move, a flow switch inside the pump senses it and the motor starts. Close the valve and the pump stops.
Some installations need a negative head pump, where the tank is not high enough above the pump for water to start flowing on its own. These start on a drop in pressure instead of on flow, which is why they behave differently when something drips.
Pumps are made for tank-fed systems only. If the house now has a combi boiler or an unvented cylinder running at mains pressure, there should not be a shower pump in the circuit at all. Pumps drawing directly from the mains supply are restricted under the water fittings regulations.
What is the pump doing?
Listen at the pump, usually in the airing cupboard, under the bath or in a loft, while someone turns the shower on.
| What happens | Most likely cause | What to do |
|---|---|---|
| Completely silent, shower barely runs | No power, or the flow switch is not sensing flow | Check the spur switch, fuse and consumer unit, then the water supply |
| Hums but does not spin | Seized impeller or failed motor | Switch off at the spur; it needs a repair or replacement |
| Starts, stops and pulses | Air in the pipes, a low tank or a weak hot supply | Check the loft tank level and the hot water from a tap |
| Keeps turning itself on when no one is using water | A dripping shower, tap or leak on the pumped pipework | Find the drip; switch off at the spur meanwhile |
| Runs but the spray is weak | Blocked inlet filters, a scaled shower head or an undersized pump | Clean the head, then have the filters checked |
| Very noisy or vibrating | Air, loose mountings or worn bearings | Check for air first; worn bearings mean a failing pump |
| Leaking or tripping the electrics | Failed seal, loose connection or water in the motor | Switch off at the spur and isolate the water; call a plumber |
Check the power safely
A shower pump is normally wired to its own switched fused spur, often outside the bathroom or in the airing cupboard. Make sure the switch is on and any neon indicator is lit. If the spur has a fuse, it may have blown. Check the rating on the pump's label or manual before replacing it rather than fitting whatever is to hand.
Then check the consumer unit. If a circuit breaker or RCD has tripped, reset it once. If it trips again straight away, or trips when the pump starts, leave it off. Water getting into the motor or a wiring fault can do that, and it needs looking at before the pump is used again.
Never take the cover off a shower pump or open its electrical connection box with the power on. If you can see water around the pump or its wiring, switch off at the spur and at the consumer unit before going near it.
Check the water reaching the pump
A pump can only boost what it is given. Run the hot and cold taps at the bath or basin nearest the shower. If those are also weak or spluttering, the problem is the supply, not the pump.
Look in the loft tank if you can do so safely. A tank that is low or empty usually means the float valve that refills it has stuck, or the mains supply was off. On the hot side, a cylinder that has not refilled, or one that was drained during other work, will leave the pump starved. Our guide to no hot water in the shower covers problems on the hot side only.
Air is the other common cause, especially after the water has been off, the tank has run low or someone has worked on the pipes. Air makes a pump surge, stop and restart, and running a pump with air in it can damage the seals. Our guide to an airlock in water pipes explains how air gets trapped and why the usual trick of connecting a hose between taps is not recommended.
Filters, the shower head and the flow switch
Most pumps have small mesh filters in the inlet connections or isolating valves. Over time they collect grit, flakes of limescale and debris from the tank, and once they are partly blocked the flow may be too low for the flow switch to start the pump. Cleaning them means isolating the water and draining the pump's connections, which is usually done at a service visit.
At the other end, a shower head choked with scale reduces flow in the same way. Unscrew it and soak it in descaler or white vinegar before blaming the pump. Our page on low water pressure in the shower covers heads, hoses and mixer valves in more detail.
If flow is good but the pump still does not start, the flow switch itself may have stuck. That is a part inside the pump and not something to dismantle yourself.
A pump that switches itself on
If you hear the pump start for a second or two when nobody is using water, something on the pumped side is losing water. It is often a shower valve or tap that has not quite shut off, a dripping shower head, or a small leak on the pipework. Negative head pumps are particularly sensitive to this because they start on a pressure drop. Our guide for when a shower keeps dripping after it is switched off explains how to track that down.
Leave the pump switched off at the spur until the drip is found. Constant short starts wear the motor, and a hidden leak can soak a floor or ceiling without you noticing.
Repair or replace?
Some faults, such as a stuck flow switch, a failed seal or a blocked filter, can be repaired if parts are available for the model. A pump that hums without turning, has worn bearings or has been run dry for a long time is usually replaced. The replacement has to be sized for the shower and the water system: a single or twin impeller, the right pressure rating, and a positive or negative head type to suit where the tank sits. Our guide to shower pump suitability covers that decision.
It is also worth asking whether you still want a pump at all. If the boiler or hot water system is due to change, a mixer shower on a combi or unvented cylinder, or an electric shower, may make more sense. Our guide to choosing a mixer or electric shower explains what each needs.
What a plumber will do
A plumber will check the power supply and the spur, confirm the tank and cylinder are supplying enough water, clear the inlet filters and bleed air out of the pipework. If the pump itself has failed, they will confirm the model and head type, isolate and drain it, and fit a replacement with new flexible connections and anti-vibration mounts where needed. They will then test the shower on full flow, check every joint for leaks and make sure the pump stops cleanly when the shower is turned off.
Get your shower working again
Loyal Plumbers covers London and everywhere inside the M25, 24 hours a day, with 10 vans on the road. We repair and replace shower pumps, clear airlocks and sort out the tank and cylinder problems that stop them working. Call 020 4652 8585 and tell us what the pump does when the shower is turned on, where it is fitted, and the make and model if you can see the label.
Our call-out charge is £60, and the engineer explains what they have found and what the work involves before starting. You can read more about our bathroom fitting and general plumbing work, or our emergency plumbing service if the pump is leaking.
Common questions
- Why has my shower pump suddenly stopped working?
- The most common reasons are a tripped circuit or blown fuse at its spur, a loft tank that has run low, air in the pipes after the water was off, or a motor that has seized. Check the power and the water supply before assuming the pump has failed.
- How do I reset a shower pump?
- Most shower pumps have no reset button. Switching off at the spur for a few minutes and back on is the only reset available. If the pump has cut out because it overheated or ran dry, it may only restart after it has cooled, and the cause still needs finding.
- Why does my shower pump keep turning on by itself?
- Something on the pumped pipework is losing water, usually a dripping shower, a tap not fully shut or a small leak. Switch the pump off at the spur until the drip is found, because repeated short starts wear the motor.
- Can I use the shower without the pump?
- Sometimes, at a much lower flow, but it depends on the valve and pipework. Some showers will not run properly without the pump. Bypassing a failed pump permanently means changing the pipework, so it is best done by a plumber.
- Is a leaking shower pump an emergency?
- Treat it as urgent. Water near a mains-powered pump is a safety risk, and a leak in an airing cupboard or loft can reach ceilings below. Switch off at the spur, close the isolation valves if you can and get it repaired.
Sources and further reading
Need help with this in London?
Emergency repairs, investigations and planned installations across London and inside the M25. Tell us what you need so we can agree the next step.
Discuss your job