If the floor only gets wet when the pressure water system has been left on, then the leak is in the pressure water system, not the holding tank. You will need to inspect the pressure water system, from the pressure pump
and accumulator tank (if you have that) to the faucets, and you will probably find a leaking hose somewhere near the wet flooring
. If there's no access under the flooring
, you may need to simply replace the hoses that are run under it.