They are machine washable. I don't wear socks with mine (KSOs) and wash them once a week -- works fine for me. Other people have found that soaking in the sink

They are machine washable. I don't wear socks with mine (KSOs) and wash them once a week -- works fine for me. Other people have found that soaking in the sink with 2-3 Efferdent (denture cleaning) tablets also works very well to control odor.