(from Heartland RVs) ...it’s not true that we (Heartland RVs) only support the fresh water tank with a piece of plywood. The plywood is an extra support that sits between the tank and the two angle irons that support the main weight of the tank. The tank phenomenon usually occurs when someone overfills their tank, or travels with it full, which “can” cause, in some instances, the tank to swell out of shape and actually bend the plywood down with it – sometimes (again not all the time) causing the plywood to slip out of its place between the two angle irons, thus, allowing the mis-shapen tank to slip down on one end or the other. This was not some huge engineering or design flaw – because this very same, exact design (with the two angle irons and plywood) has been used in this industry for decades – and still is being used. The problem seems to be that the tanks just keep getting bigger and bigger and more and more “safetys” need to be put in place to protect RVers from some of their own actions. The FACT is, we (Heartland RVs) have thousands of fifth wheels on the road with absolutely NO problems with their fresh water tanks and they are same exact design. For the record, the main “safety” that we added to our system was yet another steel bar that goes below the tank in the middle. This is a removeable steel bar – and yes, some owners have filled up their tanks so full - that they have even bent or destroyed this bar as well.