We always recommend hand-washing undies in lukewarm water with an extra-gentle lingerie wash. Gently squeeze any water out of fabric, then lay flat on a towel to dry. A detergent meant for lingerie will help elastics last longer. We can’t endorse machine washing, as it will mean that your undies meet their end more quickly, but if you must, make sure you put them in a lingerie bag so the fabric doesn’t get caught on anything. Then line dry. Never, ever put your delicates in the dryer, even on delicate.