Probably a silly question, but have you flicked up the retaining catches.?
Yes, John - but worth checking!!
Would it be any tank access Jean.?
There's an access trap within the MH but right in front of the garage. There's a screw-off lid there but I've never actually opened it. I suppose it's possible the fresh water tank goes down n back from there.
Is it likely it would be dropped in after the garage floor was fitted, and then enclosed by the removable lid? Seems counter-intuitive to me.