Hi all,
I bought one of the Lidl imersion pumps this morning and it's a powerful piece of kit. Using a 1" internal bore hose it fills my 25 ltr containers in about 20secs.
It has a one way valve that prevents water flowing back into the tank when you switch off but it will allow water to continue to syphon so you might want to fit a tap in the hose.
Hope this helps