Water collecting on bottom of 13 year old fridge

All refrigerators create water when their cooling coils shed frost build-up - that water typically collects in a tray under the fridge body through a drainage tube that exits from a collection trough inside the fridge under the coil through the back of the fridge housing.

First check the tray to be sure it is not accumulating food particles which ultimately can produce molds. Clean any water from that tray first, then look for the tube exiting on the back of the fridge see whether there is any moisture at the end of the tube under the fridge and notice whether the tray has had any recent moisture. Chances are the tube is either plugged or similarly any connector through the fridge wall.

Now, be CAREFUL not to puncture the hose or the connector with a sharp instrument however the drain path must be cleared. Try blowing through the drain inside the fridge with a straw, then add a small amount of baking soda into the collection trough, adding a small amount of water to dissolve and allow this to gradually drain out normally. Only detach the outside tube if the problem has not been resolved in this manner. The tube can be replaced easy enough, the connector through the back is another question - see you parts dealer if it has been compromised.

Good luck!