After a new belly button piercing, health professionals advise you to wait at least 3 weeks before swimming. If you have had your piercing a while, you can wear a waterproof sealed bandage around your belly button to prevent infection. Nexcare Clean Seals is a good bandage brand. After swimming, it is good to clean the belly button area with a few drops of antibacterial soap on a cottonball, and water. Also, you may clean and rinse the belly button ring as well.