First consult your bag’s instructions, which can be found on the label or online. Next get the right cleaning product--a product made specifically for washing down or synthetic sleeping bags. Run the bag through the gentle cycle of the washer. Then put it through a second rinse cycle to make sure all soap is removed. Gently squeeze away the excess water.
To dry, place the bag in a commercial-sized dryer (perhaps at a laundromat) on low heat. A synthetic bag will take an hour, while a down bag will take several hours. For dow bags, add two or three clean tennis balls to help break up clumps of down.
Begin by filling your bathtub with cool or warm water. Add the proper cleaning product for your bag, avoiding using an excessive amount of soap. Lay the bag in the water and gently work the soap through the whole bag. Rub together the most soiled areas. All the bag to soak for up to one hour.
Drain the tub and press out the remaining water. Then fill the tub with cool or warm water again to rinse. Work the soap out gently, let the bag sit for 15 minutes and drain. Press out the remaining water and repeat this process until the soap is gone.
If your home dryer is too small the bag will stay balled up, so you’ll need to bring it to the laundromat. However, if your dryer is large enough, use low heat and let a synthetic bag dry for an hour and a down bag for several hours.
If your choose not to use a dryer, lay your bag on a clean surface with low humidity and no direct sunlight. You’ll need to manually break up clumps of insulation as it dries.