My Pump Has Stopped

My pump has stopped working:

submersible-fountain-pumps,  pictures courtesy Hozelock & Oase

Typical submersible fountain & water-feature pumps The strainer is fitted near the front of the pump casing

pumps for filters, pictures courtesy laguna & oase

Typical submersible pumps for filters & waterfalls

The pump is fitted inside a coarse strainer casing


If the flow has gradually dropped over a few days, this suggests clogging of the inlet strainer. Disconnect the power to the pump before handling. Clear the pump strainer of debris, and then reconnect the power. If the flow is only partly restored, dirt might have built up inside the casing, or clogged the pump/rotor or an outlet valve, and a more thorough clean of the pump might be in order.  © www.watergardensolutions.co.uk


A small magnetic rotor/impellor   A larger ‘open’ impellor/rotor   A larger ‘closed’ impellor/rotor

The moving part of the pump is the impellor (sometimes propellor-like), it spins to move the water. It is fixed to the rotor (often a magnet or a cylinder of metal), that fits inside the pump body. In many pumps (but not all), it can be removed for cleaning or replacement. Check the manufacturer’s instructions or guide-book for details.


Most modern pumps have a built-in thermal cut-out that turns off the pump if it starts to overheat. Let the pump cool down. Turn it off for a while to cool and re-set. Clear any debris and then try turning it back on, it may restart. Overheating can be caused by clogged strainers or dirt building up in/around the pump. A thorough clean will often help.

Overheating also results from wear and tear, or scale building up on the rotor and bearings. Some manufacturers sell special cleaners that the pump can be soaked in, and these help to safely remove the scale. Wearing parts can sometimes be replaced to prolong the life of the pump.

Drawing in Air?

If the pump is drawing in air, for example if it has started to run dry, it may also overheat. Some newer specialist pumps have electronic controls that detect if they draw in air, and turn them off and then back on again a short while after, to try and expel air bubbles from the system. However, they often shut down completely if they have been drawing air for too long. In these cases, turn off the pump at the mains to allow it to re-set, check that the pump cannot draw in more air, and then switch it back on to see if it will restart.

Trip Switch?

All outdoor equipment should be protected by an RCD (Residual Current Device) “trip-switch” which is included on all new installations, but might be missing on old installations. The RCD can be a switch on your electric distribution board, or a device built into a plug or socket. It is distinguished by a “Test” button.

If a fault has been detected, the switch will trip out, turning off the connected power. Sometimes the switch will trip even if there isn’t a fault - perhaps due to a short power-cut, or a lamp failing at the end of its life. Some types of RCD are “non-latching”, which means that they need to be manually turned back on (or re-set) after any power failure. © www.watergardensolutions.co.uk

Check if some obvious damage has caused the RCD to trip out e.g. due to a spade cutting through the cable, or rainwater entering a connection. If the RCD has tripped for no obvious reason, and everyone is safely out of contact with the wiring and the pond, try turning it back on. If the power restarts the pump, perhaps there was no fault. Check that the RCD is functioning correctly by pressing the test button. It should trip out. It can then be turned back on. ©

If the trip switch cannot be turned back on, because it immediately cuts off the power again, or cuts out again a short time after, then there is a fault with the circuit or the pump. Do not continue to run the pump. Turn off or disconnect the power to that circuit and get it checked.


If the power-switch is on, and RCD latched on, but there is no movement from the pump, the fuse in the plug/socket/switchbox may have blown, or the overload trip-switch on the distribution board might have shut off. If fuses/overload-switches trip repeatedly, you must turn off the circuit and have it investigated.

If the pump still doesn’t run even though the RCD and fuse/overload indicate no problem, the pump may have failed. Disconnect the power and get the pump checked. ©

N.B. Mains power can be very dangerous if mishandled. Always disconnect the power before handling the pump or working in the pond. If in any doubt about electric wiring or appliances – call in professional help.

Where to get help?

In the UK, your first port of call should be the shop or installer who supplied the pump. They should handle any warranty issues, and may be able to supply spare parts. The more reputable manufacturers often have downloadable copies of the instruction guides on their website, or a help-line to call for advice. If it is an electrical problem with the cabling or junctions, your local electrician should be able to help. ©

What about the fish?

If your fish are used to having moving water from a filter, fountain or waterfall then the failure of the pump might cause problems, especially in hot weather. Ideally fit a temporary backup pump or an economically priced air-pump with airstone (available from specialist aquatic suppliers), whilst you sort out the main pump problem. In the short term, see the FAQ sheet “Help, there is a power failure

Contact Us if you would like to arrange a service of your pump or filter system.


See more Frequently Asked Questions

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