Most water pump problems come from power, priming, blockages, worn parts or dry running; check power and controls first, then suction and discharge, and stop and call a technician if you smell burning or hear grinding.
Safety first: isolate power before touching any pump. Never open electrical parts unless you are qualified.
| Symptom | Likely causes | What to check | Next step |
|---|---|---|---|
| Pump does not start | No power, tripped breaker, failed float or pressure switch, capacitor | Power supply, breaker, float / pressure switch | Reset; replace faulty switch or capacitor |
| Motor hums, does not turn | Jammed impeller, failed capacitor | Isolate and turn shaft by hand | Clear blockage; service pump |
| Runs but no water | Lost prime, suction air leak, blocked strainer, closed valve | Suction pipe, strainer, valves, water level | Re-prime; clean strainer; fix leak |
| Low flow or pressure | Worn impeller, partial blockage, undersized pipe, low voltage | Discharge valve, filters, voltage | Clean; replace worn parts |
| Pump cycles on/off rapidly | Faulty pressure switch, waterlogged tank, leak | Pressure kit, tank pre-charge, leaks | Adjust or replace controls |
| Overheating / trips | Dry running, blocked impeller, low voltage, bad bearing | Water level, amps, temperature | Stop and service |
| Loud noise / vibration | Cavitation, bearing wear, loose mounting | Suction conditions, base, bearings | Fix suction; replace bearings |
| Water leaking at the shaft | Worn mechanical seal | Seal area, oil chamber | Replace seal |
| Pump runs but sump will not empty | Check valve stuck, clogged outlet, float stuck | Non-return valve, float, discharge | Clean or replace |
| Sewage pump blocks | Wipes, rags, wrong pump type | Impeller / cutter | Clear and consider a cutter pump |
How to prevent most faults
- Use the right pump for the liquid.
- Protect against dry running with floats or pressure controls.
- Keep strainers clean.
- Fit non-return valves.
- Service pumps on a schedule — see our maintenance checklist.
If the pump needs more than a quick check, our team can collect, repair or replace it — see pump repair & service.
Frequently asked questions
Why won’t my water pump start?
Check power, breaker, float switch and pressure switch. If the motor hums but does not turn, the impeller may be jammed or the capacitor may have failed.
Why does my pump run but give no water?
The pump may have lost prime, the suction pipe may leak air, the strainer may be blocked or the impeller may be worn.
Why does the pump keep tripping?
Overload from a blockage, low voltage, damaged winding or a bearing/seal fault can trip the protector.
When should I call a professional?
If you smell burning, see water in the oil chamber, hear grinding or have repeated tripping, stop and call a technician.