Its is recommended to wash Down comforters as infrequently as possible. Maybe once every four years. Taking care of them involves fluffing them 2 or 3 times a week and keeping them covered to minimize the need for cleaning.

Typically the problem lies not in the washing but in the drying. How to prevent clumping.

Washing in a machine:
1. A useful trick to start with is to fold the comforter and put it in on the final spin cycle. This will flatten it and take the air out. This will make it easier to get it into the machine and soak the water.

2. If you have to stuff the comforter in to get it inside then you need to go to a laundromat to use a large machine.

3. Before putting the comforter in - Let the machine fill warm with water and add the detergent. The comforter will absorb all the water and so putting it in first will prevent the detergent from mixing.

4. Use a mild liquid soap detergent. You want to clean the comforter but you do not want to strip the feather down of its natural oils. If you must use a bleach - use a non chlorine one but it would be better to spot spray with a fabric cleaner before washing.

5. Use a delicate or gentle cycle - no agitating.

6. Rinse twice to ensure all detergent is flushed away.

7. If your machine has two spin cycles. Stop it after the first gentler spin. Take the comforter out and press or wrap it in heavy towels to remove excess water and then put it back in for the final spin.

Dry Cleaning:
This is the recommended method due to the difficulties of washing the comforter yourself.

Drying:
It is very important that the comforter is fully dried. If not then mildew may develop and destroy your comforter.
1. Do not use dryer sheets you do not want a coating on the feathers.

2. After removing from the washing machine put it a large dryer. Once again a Laundromat is good for this.

3. Use a medium heat. Put two white tennis balls in with the comforter. They will fluff and prevent compacting of the down.

4. It will take a while to dry - maybe up to 3 hours. Take it out every 45 minutes or so and fold it and redistribute the down if it is clumping. This is optional but may give a better result.

5. When finished - put it back on the bed. There maybe some small amount of moisture left in the comforter and so its a bad idea to pack it away immediately. Leave it on for a week,

I have a very similay down comforter, and Yes they can be washed. Throw it in the washers, follow lable direction if you have them, set the gentle cycle and there you go. Do wash by itself. Merry Christmes.