Depends on each one's habits, but around here washing such a big comforter would be a "special cleaning day" type of thing, to happen just once in a year or couple of years (or even more, if it has been kept clean). So e.g. after the winter finishes, before putting the heavy clothing away in a closet for the summer, you might bring it to a laundry shop for cleaning, which usually has huge front loaders: https://previews.123rf.com/images/toonpang/toonpang2008/toon...