Hi,

Self defrosting refrigerator go into a defrost cycle to melt the frost that builds up on the evaporator coil in the freezer section.

The water created from the frost melting during the defrost cycle should run down a drain tube to the bottom of the refrigerator into a drain pan were it would evaporate.

Sometimes the drain tubes can get restricted or plugged up and then the water from the defrost cycle sometimes runs other places instead of into the drain pan.