Water Pump Not Working? Troubleshooting Guide.
Water Pump Not Working?
Start with the symptom before replacing the pump.
A pump that will not start, runs without water, loses pressure, trips power or makes unusual noise does not always need replacing. The problem can be the water source, suction line, valves, controller, electrical supply, pipework or the pump itself.
What Is the Pump Doing?
Choose the closest symptom. We will show the first checks that make sense before you assume the pump has failed.
Select the closest symptom above
The most likely first checks will appear here.
Before You Replace the Pump
Check the simple external causes first. A new pump will not fix an empty tank, closed valve, blocked filter, suction leak, damaged controller or electrical supply fault.
Water Source
Confirm the tank or supply actually has water and that the pump inlet is not starved or blocked.
Valves & Filters
Check isolation valves, non-return valves, strainers and filters for closed positions or restrictions.
Power & Controls
Check the pump has power, the controller is active and no overload, breaker or RCD has operated.
Do not keep resetting a pump that repeatedly trips, smells burnt, has damaged wiring, has water entering electrical components or becomes excessively hot. Electrical and pump faults should be assessed safely by an appropriate licensed person.
Water Pump Troubleshooting by Symptom
| Symptom | Common Things to Check | What It Can Point To |
|---|---|---|
| Pump will not start | Power point, breaker/RCD, controller, pressure switch, tank level, dry-run lockout | Electrical supply, control fault, motor/overload or protection state |
| Pump runs but no water | Tank level, suction valve, prime, air leaks, blocked inlet, non-return valve | Loss of prime, suction leak, blocked line or dry source |
| Low pressure / low flow | Filters, valves, pipe restriction, suction condition, pump curve, multiple outlets | Restriction, worn pump, undersizing or higher-than-expected system head |
| Keeps losing prime | Suction fittings, foot valve/non-return valve, pipe joints, water level | Air leak or water draining back from suction line |
| Trips power | Do not repeatedly reset; inspect for water ingress, overheating or electrical fault | Motor, cable, capacitor, overload, controller or supply fault |
| Noisy / vibrating | Mounting, pipe strain, suction restriction, air, low water level, bearings | Cavitation, mechanical wear or installation movement |
| Pump leaks | Fittings, unions, seals, drain plugs, housing | Loose connection, seal failure, cracked fitting or pump-body issue |
| Won't stop / odd control behaviour | Leaks downstream, controller, pressure tank, non-return valve, pressure switch | Control or system-pressure issue |
Why a Pump Runs but No Water Comes Out
This is especially common with external rainwater pumps because they rely on a sound suction path and correct priming.
Empty or Low Tank
If the inlet is exposed or drawing air, the pump cannot move water properly and may trigger dry-run protection.
Loss of Prime
An external self-priming pump still needs a suitable water-filled suction path. Air leaks can prevent or destroy prime.
Blocked Suction
Strainers, tank outlets, valves or pipework can become blocked enough to starve the pump.
Why Water Pump Pressure Drops
A pressure drop does not automatically mean the motor is failing. First work out whether the pump is being starved, restricted or simply asked to deliver more flow than before.
Blocked Filter
A loaded filter can create substantial pressure loss and make the pump appear weaker.
More Outlets Running
Higher simultaneous flow moves the operating point along the pump curve, usually reducing available pressure.
Pipe or Valve Restriction
Partially closed valves, crushed pipe or small pipe can increase system head and reduce usable flow.
When Replacement Makes More Sense
Internal Mechanical Failure
Worn bearings, damaged seals, impeller damage or repeated motor faults can make replacement more practical than repair depending on the pump.
Wrong Pump for the Job
If the existing pump has never delivered enough flow or pressure, replacing like-for-like may repeat the same problem.
Old Pump + Control Problems
Where both pump and controller are ageing or unreliable, replacing the complete setup may give a cleaner long-term result.
If the existing pump always worked well, its performance is useful when choosing a replacement. If it always struggled, re-size the system from required flow, pressure and head instead of simply buying the same pump again.
Compare Replacement Pump Categories
If replacement is required, choose by water source and application rather than brand alone.
Water Pump Troubleshooting FAQs
Why is my water pump not turning on?
Check the electrical supply, breaker or RCD, controller status, pressure switch and any dry-run or overload protection. Repeated electrical tripping should be assessed rather than continually reset.
Why does my pump run but no water comes out?
Common causes include an empty tank, loss of prime, suction air leak, blocked inlet, closed valve or failed non-return valve.
Why has my water pump lost pressure?
Check filters, valves, suction conditions, pipe restrictions and whether more outlets are running than before. Pump wear or undersizing can also reduce performance.
Why does my rainwater pump keep losing prime?
Air leaks on the suction side, a failed foot or non-return valve, poor suction layout or low tank water level can allow the suction line to drain or draw air.
Why does my pump keep tripping the power?
Possible causes include an electrical fault, motor overload, damaged cable, water ingress, controller fault or a failing motor component. Do not repeatedly reset a faulting pump without assessment.
Why is my water pump suddenly noisy?
Noise can come from cavitation, air in the suction line, loose mounting, pipe vibration, worn bearings or other mechanical damage.
Should I repair or replace my water pump?
That depends on pump age, fault type, parts availability, repair cost and whether the existing pump was correctly sized. If the old pump never performed well, re-size before replacing it.
Why will my pump not stop running?
Possible causes include a downstream leak, controller or pressure-switch issue, failed non-return valve, pressure tank problem or a pump that cannot reach its shut-off condition.
Diagnose the System Before Replacing the Pump
Check the water source, valves, filters, suction, power and controls first. If the pump itself has failed, replace it with a model matched to the actual application and required duty.
