If you’ve had your bulky down comforter on your bed for a while now, it’s a good idea to give it a trip to the laundry. The best way to get it clean is to take it to the laundromat, and use one of their larger machines. Running your comforter through your home machine can crush and damage the filler. Use warm water and the delicate cycle and check the care label for drying instructions.
Keeping your comforter in a duvet cover on your bed will also help it stay cleaner, longer.