If you open your refrigerator to find puddles of water on the shelves, running down the walls, or accumulating in the lower vegetable drawers, then you obviously have some kind of problem. Odds are it's nothing too serious, but it's a problem that causes a constant mess, and the water may even run out the front door of your appliance and cause damage to the floor in your kitchen. Make diagnosing the source of the accumulating water a top priority.
Clogged Drain Tube
If you're seeing puddles of water in the bottom of your refrigerator, it's likely that the problem is up above in your freezer. Under normal circumstances the defrosting system in your freezer will turn on a heater several times a day and melt off frost that accumulates on the evaporator coils. As the frost melts into water, the water is channeled into a drain tube that leads to a drain pan in the bottom of the refrigerator. There the water evaporates from heat. But if the drain in the freezer becomes clogged, the water will simply run over and wind up dripping into the refrigerator below. Eventually it makes its way to the bottom. You will have to clear the clogged drain. Most likely it's simply iced over. Pouring a little hot water into the drain will clear it out and solve the problem.
Excessive sweating inside the fresh food compartment could cause water accumulation in your refrigerator. If you notice the walls of the refrigerator getting wet, then there's probably an issue with the door gaskets. The rubber gaskets surrounding the door opening keep outside air from getting into the refrigerator when the door is closed. If the warmer air from outside is allowed to enter the refrigerator consistently, the walls can begin to experience condensation. The moisture eventually develops droplets and runs down the walls, pooling at the bottom of the unit. Replacing the worn gaskets is the only solution to this problem.
If your refrigerator has a water dispenser built into the door, then it's possible that accumulating water could result from a leak in the dispenser system. The water dispenser could have a bad hose connection or the tubes that carry the water through the refrigerator for chilling could be leaking and dripping into the main compartment. This may be an obvious leak or one that requires taking the panels off the refrigerator to locate. If you can't see the problem yourself, consult a professional appliance repairman.
If you simply can't find a physical problem with your refrigerator and you still find water accumulating in the refrigerator, check the obvious. If you keep a container of bottled water, especially the large type with a spigot on the side, check to see if it's leaking. These water containers often have slow leaks if they aren't closed properly. It may have also been damaged in transport from the store. A few drops here and there can lead to big puddles over time.