Straw sippy cups often come with multiple pieces, like a valve, straw, or even weighted piece. With so many pieces to wash, straw sippy cups can easily become a breeding ground for bacteria and mold. They are sanitary to use for infants, but only with the proper care and cleaning.  To keep your baby’s straw sippy cup sanitary, always rinse immediately after use to prevent mold from setting in. If you can’t rinse, allow the cup and its pieces to soak in soapy, hot water before cleaning them with a straw brush. Once you’ve finished cleaning them by hand, place them in the dishwasher to be sterilized, which can help kill any bacteria left behind.