If bras weren’t made to be washed, they would be made totally different that they are. Just like your clothes and other undergarments, they should basically be washed after a days wear. An exception would be, only because bras are worn covered by other clothing, AND aren’t wrapped around the behind, one could be worn a couple days before having to be washed, IF you don’t sweat much at all that first day. If we were to rewear a bra we sweated in the day before, we might as well wear the dirty top too. Wash all bras on delicate cycle or “hand wash” cycle, light on the detergent, hang or lay flat to dry. (The heat from dryers is what would disintegrate the elasticized materials).