"I never saw a system anywhere for doing the pumping of the water from barrel to aircraft by anything other than hand-pump and it was an absolute sod of a job."
A very few, possibly only one, of the BIA aircraft had a portable electric pump that plugged into a socket in the forward hold. Naturally, they or it were the F/O's favourite aircraft.
It might be apocryphal but after the Monarch 1-11 wheels up at STN the aircraft was repaired and returned to service. On the first trip the F/O was duly despatched to pump in the demin water but returned to the flight deck to say he couldn't find the filling point. The captain, muttering something on the lines of 'stupid boy', went down and couldn't find it either. It turned out that the repairers had skinned it over. Much recalculation to see whether they could get out dry.