Welcome to the JOF. It is very likely you will hear from other 19RD owners. It is likely none of them have their water tank & underbelly resting on their axle.
So, to answer your second question, 'No, it is not OK.'
You'll probably need to remove at least part of the underbelly material in order to see why the tank support has failed.
Sherm & Terry w/rescues Steve (std Poodle) & Eydie (min Schnauzer)
2015 Jay Flight 27RLS (Camped: 102 nights 2015, 90 nights 2016)
2006 Ford F350 6.0 PSD, Lariat, 4WD, CC, LB, SRW, auto., Camper pkg.