Shower Pump Not Working — No Pressure or Flow
Check the steps below first — if you're not confident, get it fixed safely today.
Post a job — we'll find you an engineer →Always isolate the electrics at the fused spur before touching the pump. Never run a shower pump dry — it will burn out in seconds.
Shower pumps are brilliant for boosting water pressure, but when one stops working, it's frustrating and often baffling. The good news is that most no-flow or no-start problems are straightforward to diagnose without calling an engineer immediately. Homes with low mains pressure, older plumbing systems, or those relying on a cold water storage tank upstairs are most prone to pump issues. This guide walks through the most common culprits—from simple isolation valve oversights to airlocks and blocked filters—that account for the vast majority of failures. Many faults are fixable in under an hour with basic tools, though if the pump motor has genuinely failed, replacement will be necessary and is best left to a qualified plumber.
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Most likely cause & what to check
Check the isolation valves on both the hot and cold inlets to the pump are fully open — the slot in the valve head should be in line with the pipe. A partially closed valve is the single most common cause of no flow.
Check the pump fused spur switch (usually on the wall nearby) is switched on and the fuse hasn't blown. Replace with a 13A fuse if needed.
Look for an airlock: if the pump hums but no water comes out, there is likely air trapped inside. Close both isolation valves, carefully undo the inlet union nuts one at a time, allow water to flush through briefly to purge air, then refit.
Check the cold water storage tank in the loft — if the tank is empty or the ball valve has stuck, the pump has nothing to draw from.
Inspect the inlet strainer filters (inside the pump union connections) — these small mesh screens block debris. Remove, rinse under a tap, and refit.
If the pump still does not start, the impeller may be seized or the motor has failed. At this point the pump usually needs replacing — a plumber can confirm with a flow test.
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Frequently asked questions
How do I know if my shower pump is actually broken or just needs troubleshooting?
If the pump is humming or vibrating but no water is flowing, it's almost certainly not the motor—an airlock or blocked inlet is the likely cause. If the pump makes no sound at all and the fused spur is switched on with a good fuse, then the motor may have failed and you'll need a professional diagnosis.
Can a shower pump be damaged by running it dry?
Yes—absolutely. Running a pump without water will burn out the impeller and motor in seconds, causing permanent damage. Always ensure your cold water storage tank has adequate water and never isolate the inlets unless you're actively troubleshooting an airlock.
Why has my pump suddenly lost pressure when it was working fine yesterday?
Sudden loss of flow usually points to an airlock, a blocked inlet strainer, or an isolation valve accidentally closed partway. Start by checking both inlet valves are fully open—the slot should be in line with the pipe—and inspect the strainer filters for debris or sediment.
Do I need an electrician to check the fused spur, or can I do it myself?
You can safely check and replace the fuse yourself—it's a 13A cartridge fuse and takes seconds. However, always switch off and isolate the spur before touching the pump itself, and if the fuse blows again immediately after replacement, stop and call a Gas Safe engineer, as there may be an electrical fault.