Most of us are wearing a mask these days when we're out and about. Along with social distancing, handwashing and other safety measures, masking up is one of the best things we can do to help slow the spread of COVID-19.
In the washing machine. Just toss your mask in with the rest of your clothes when you run a load of laundry. Regular detergent is fine to use. If you know the type of cloth the mask is made from, use the warmest water setting that's appropriate for that material. When drying the mask, use the highest temperature setting.
By hand. First, prepare a diluted bleach solution (such as 1/3 cup of disinfecting bleach to a gallon of room-temperature water). Make sure the bleach contains 5.25% to 8.25% sodium hypochlorite. Soak the mask in the bleach solution for 5 minutes. Next, pour the bleach solution down the drain, and rinse the mask with water.
You can toss the cleaned mask in the dryer or you can air-dry it, ideally in direct sunlight.
Whichever cleaning method you use, make sure the mask is completely dry before you put it on.