Not true, Mr Red. Hotties are available at The Warehouse stores, in winter. Two different brands, at different times.

Unfortunately, the screw plugs of these two brands are NOT interchangeable, although the SEEM to fit. You have been warned.
Water can be removed from a mattress, more-or-less, with a wet-and-dry shop vac.
But not invisibly.

Her Indoors prefers not to have the bed connected in any way to a 240volt supply.