A puddle is an outlet problem, not a water problem
The back wall of a fridge is the evaporator, and it is colder than the air around it, so moisture from the food and from every door opening condenses on it and freezes. Every few hours the compressor stops and that ice melts, and the meltwater runs down the wall into a channel formed along its base, collects at the lowest point, and leaves through a hole the size of a pencil.
From there it goes down a tube into a shallow tray sitting on top of the compressor, where the compressor's own waste heat evaporates it back into the room. That is the entire system, and it has exactly one path. There is no overflow, no second drain, no margin. So when the hole blocks — with a leaf of cabbage, a crumb, a film of mould, a piece of packaging — the channel fills, the water rises above its lip, and it runs down the inside of the fridge to the lowest place available, which is under the bottom drawer.
Which means the puddle is not telling you that too much water is getting in. It is telling you where the water got to when it could not get out. That distinction matters because almost every wrong answer on this page comes from assuming the first: people re-seal the door, turn the thermostat up, cover every container, and the puddle comes back, because none of those things was ever the problem.
Where the water is decides which fault it is
Water standing in the channel, level with the hole is a blocked drain, and it is the common one. Clear the hole with a soft tube and warm water and it is fixed for nothing. A back wall covered in thick frost is the defrost system, and the water appears suddenly when it finally melts in a slab — that is a different job, and it starts with a full defrost and a look at the door seal, because a seal that leaks lets moist air in and that is what turns into frost.
A channel that is bone dry with water on the floor by the door is not a drain fault at all. It means the fridge is leaning, so the meltwater runs forward instead of back, and it escapes past the seal. Fix that with the feet: a fridge should tilt very slightly backwards so the door closes itself. A dry channel and water underneath the cabinet means the drain tube has come off or split inside the machine, and that is a service call, not a jug of water.
Never rod it with wire
The drain is a soft corrugated plastic tube a few millimetres across, and on most models it has a U-bend in it to stop fridge air escaping into the room. Wire goes in easily and comes out with a hole in the tube, or does not come out at all. Either way you have turned a blocked drain into a leak inside the cabinet, which drips onto the floor from underneath and is a much bigger repair than the one you started.
What works is a length of soft tubing — aquarium air line, a syringe with a piece of hose pushed over the tip, or a dedicated drain brush — plus warm water, not boiling. Warm water softens the debris and the tube, and gentle pressure from a syringe clears most blockages in one go. If the water will not go down at all, and the fridge has been cold, the tube may be frozen rather than blocked: switch the fridge off for a few hours, let it thaw, then flush it. And put a jug underneath to catch what comes out.