I have a sub zero 611 and water is accumulating

sounds like you have a blocked drain tube....when defrost system kicks in the melted water runs down a tube into a tray adjacent to the compressor and is evaporated by the heat. when the tube becomes blocked the water has nowhere else to go except overflowing and out through the refridge vent down the back and onto the floor of the refridge.

If you are hand with tools i can explain a procedure to fix this problem, If not call a service guy :)