A humming sound usually means the pump is being powered but water isn't moving correctly through the system. Common causes include an air lock, incorrectly seated water tank, restricted water filter, limescale build-up or a blockage within the water circuit. Check the water supply and filter before assuming the pump itself has failed.

Yes. If air becomes trapped in the hydraulic circuit, the pump may run without being able to draw water properly, often producing a louder humming or buzzing sound. This can happen after the water tank has run empty, following maintenance or after changing a water filter. Running the hot-water function can help prime the system and restore water flow.

Yes. An incorrectly fitted, blocked or poorly primed water filter can restrict the supply of water to the pump. If the problem started after changing the filter, remove it temporarily and test the machine without it. If water flow returns, correctly prime or replace the filter before refitting it.

Yes. Heavy limescale can restrict narrow passages within the water circuit until the pump struggles to move water through the machine. If water flow became progressively slower before stopping completely, scale or another internal restriction is particularly worth investigating.

When the tank runs empty, the pump can draw air into the water circuit. Refilling the tank doesn't necessarily remove this trapped air immediately, so the pump may hum without producing water. Refill and correctly seat the tank, then use the hot-water function to help draw water through the system and prime the pump.

Not necessarily. The fact that you can hear the pump doesn't confirm that it is mechanically healthy, but water-supply problems should be ruled out first. Check the tank, filter, priming and accessible water paths. If the machine remains unable to move water after these checks, the pump, valve, flow system or another internal hydraulic component may require further diagnosis.