O.K., gotcha, refrigerator only. Mine's quite large, and on trips I always start it off with a couple of blocks of ice in the bottom, and I usually have a large bag of cubes in there, too. It's moist, and as the ice melts, it needs a place to drain. Many boat fridge designs started life as ice boxes, too. I guess that's why they have drains, and also to ease cleaning.