The Water pump in my Swift Challenger 530se appears to be continually on making a humming sound even when all taps are turned off. I now have to turn the main pump switch on and off each time I want to draw water from any taps to avoid the continuous humming. It's hardly a major problem but tends to niggle me after doing it for the umpteenth time over the course of a weekend. (the water level in the aquaroll is always adequate)