Down comforters, if properly cared for, will last a good long time.
The following tips may help:
A duvet cover for your down comforter can protect it from body oils,
dirt, and dust. Comforter covers with pore sizes smaller than 10
microns can provide protection from dust mite allergens as well.
A wide variety of beautiful covers is available in just about any fabric;
these duvet covers will add color and design to your bedroom, and many
of them can be washed frequently.
If your comforter does become soiled, spot treat it promptly with
warm water and a mild detergent. Pull the soiled fabric area away
from the underlying down and feathers, carefully moisten and clean the
affected area, and blot it dry with a clean, colorfast towel. Hang
it out to dry in a warm, well-ventilated location.
Shaking your down comforter frequently will keep the down fluffy
and keep it from bunching up and clumping together.
From time to time, air out your comforter by shaking it out
a window or hanging it on a clothesline. This will help to keep
it fresh and sweet smelling.
A down comforter may be washed in a large size
Spot treat any stains and wash it in cold water. Dry it in a dryer
on a low heat setting, adding a few clean tennis balls to keep the down
fill from matting together as it dries. If no tennis balls are
available, you may periodically remove the comforter from the dryer
and shake it during the drying process.
If you prefer not to wash your comforter, it may be dry cleaned
periodically every few years.
Store your down comforter in a dry, ventilated place when you
are not using it.