Welcome to Just Answer..Most common problem when this happens is the defrost drain inside the freezer is blocked..When the unit defrosts...The water has no where to go due to the blocked drain..The water then backs up onto the freezer floor eventually making its way out the door onto the kitchen floor..The leak could also be coming from the defrost drain hose..The defrosted water exits out the freezer to the underneath area of the fridge into the holding pan below..Make sure the hose is directly over the pan itself.What is the model number of your fridge..? Thanks Bob

If the defrost drain hose is leaking you basically will not see water all the time..Remove the front lower panel..Take a flashlight and inspect around the area of the hose as it exits out the bottom of the freezer area.

If your fridge has a ice maker..Allot of times the clear plastic waterline can get pin holes in it..Once again it would be hard to detect as the ice maker itself does not cycle as often as using the dispenser water option..Let me know what you find out after inspecting with your flashlight..Thanks Bob