Thanks Cap'n !
Have also seen that mentioned on one of these forums (can't remember which one) so will see what other alternatives there are. Seems NB tho' that the hose from the tank to the kitchen can withstand a bit of repetitive flexing. Have seen some blue ones at a boat supply recently but was the wrong size.
Also read that it's better to keep the water tanks full, so no air available to promote growth in long term storeage.
Over the w/e I did a Tank Cleen treatment, followed by two flushes of the water tanks and refill, so for the moment will leave them full.
I see there is black conduiting over the hoses from the filler to the tanks, so that's probably why.
Amazing how one's to do list keep growing, all good fun though!