The first thing that you need to do is find out where the leak is coming from. See if one of the following will solve the problem. 

See if the drain pan is full

The water collected during defrosting goes to the drain pan, which is usually near the bottom of a refrigerator. If your appliance is unbalanced, water may spill from this pan.

Try rocking your refrigerator very slowly to see if it is unbalanced. If it is easy to rock it, then it is not balanced. You can level it easily by screwing the feet up or down until it is balanced. Keep in mind that the ground should also be level. Relocate the appliance if necessary. 

See if the leak is coming from the inside, behind the crisper drawers

Water collected during defrosting may go through a tube inside your appliance. This tube reaches a drain under the crisper drawers. Remove the drawers to see if the water leak is coming from this drain. If there’s a water puddle here, this probably means that there’s a clog in the drain.

You may try to unclog the drain with a plumbing snake (sold in hardware stores). Insert it through the drain, push it until it meets the clog and turn it clockwise. Pull it out and repeat this process until the clog is removed. Try pouring some warm water down the drain to see if it is unobstructed.

If your fridge is plumbed, check the water connections

If your refrigerator has a plumbed-in water dispenser, the leak may be coming from its water line connections. These vary depending on the model. Follow the instructions in your appliance’s user manual to see how and where the connections are. If you’re having trouble finding your manual, download it here using your product’s model number. Check that these connections are correctly in place and not obstructed.