Not sure of your fridge model, but my Norcold 2118 always had water in the bottom of the cabinet.
Main cause, poor design. When the fridge defrosts, the condensate would run down the back of the cabinet instead of dripping into the drip tray. To make matters worse, the door alignment was off and the center flap wouldn't seal properly allowing humid air to build up excessive frost on the fins and would also not allow the fridge to cool properly.
I added a strip of white tape to the cabinet above the drip tray (see photo) so when it defrosts the condensate actually drips into the drip tray. Also, verify your door/s are shutting and sealing properly. Mine required shimming up the left hinge.