Boom goes my fresh water tank....

In my '05 Montana 32' 5er the fresh water tank is in the very rear. We have always traveled with full since new and no problems. The one time I let it get to about half full on a trip ti Maryland I found it had shifted side ways when we got home. I assume it shifted from the water slouching around. When I pulled the under cover down I saw the the tank was several inches narrower than the frame width and not blocked in any way. I move tank back to where it needed to be and put blocks at both ends. I also reenforced the supports under the rest on the tank as an extra measure while I was under there. That was 4 years ago and no movement since. Still leave home with it full reguardless of how long we will be gone. Last year we pulled into a park in Missoula, Mt. behind another long rig and when the pulled into their spot they run over the water connection and broke it. This action shut our spots water off too, so glad I had water onboard to use till it was fixed. On our 27' tt we had the water tank was in space under the bed which was in the back. This is my experience.