Need to know why refrigerator is leaking water into drawers and shelves?

Leaking water indicates outside air getting into the unit.

Check the rubber seal around the door. If it's cracking, or hard, it's time to replace the rubber, or the unit itself. IF the rubber is hard and cracking, perhaps you should get a new unit, as it won't be long before you start having compression problems, or even cooling problems.

It could also be that the "grill" on back OR under the unit is filthy and needs to be cleaned.

I don't know, but I had to get a new refrigerator because of that. It was something about the drainage thing kept freezing up and my crisper drawers would fill with water. Also the bottom shelf with have a layer of ice.