I guess the general idea is supposed to be you never need to check it. The water ends up in that pan somewhare at the back/bottom of your refrigerator, and the heat from the compressor below it evaporates that water away (and this helps also to cool the compressor down as it takes energy to heat and evaporate the water; simple physics, yay!).

I've seen some commenting that their water pan is usually completely dry, ie. the water evaporates faster than new comes from within the refrigerator. Maybe this depends both on the model, what you keep inside the fridge (my wife puts quite a lot of fresh vegetables there, maybe they cause more water to accumulate), how hot the compressor works etc.

With my earlier refrigerator, I never checked it either as the fridge was situated so that I would have had to pull it out completely in order to see at the back of it. But now that I can more easily check it in this new model, I guess I check it from time to time, at least so that it doesn't seem to be spilling over.

There is not much chance of it really spilling over though unless there was lots of water coming in constantly, as there seems to be two backups for the spill. If the pan is about to spill over, there is a small cap at one side which leads to yet another pan where all the excessive water would go, and even that has a backup pan on the side to which water would go if even that would spill over. I saw some dry stuff on the bottom of that third pan, so apparently at some point both of those first two pans have spilled over, ie. there has come quite a lot of water from within the fridge at some point, but then stopped.

Technology, bah...