You can sterilize your child’s sippy cups to help reduce mold growth. You can do this once a week or a few times a month.If your dishwasher has an extremely hot setting, that may sterilize the cups.
You can also try a steam sterilizer.
 A diluted bleach solution can sterilize the sippy cup and help remove mold. To make the solution, add one teaspoon of bleach to a gallon of water.Soak the sippy cup parts for two minutes.
Remember, don’t mix bleach with any other household cleaners. That can cause toxic fumes.
Rinse the cup very well after you soak it in a bleach solution. Let the cup dry completely before you reassemble it.
 Vinegar baths can help reduce mold growth. However, vinegar will probably only kill about 70 percent of mold.To give the cup a vinegar bath, add one part vinegar to three parts hot water. Let it soak for a couple of minutes.Rinse the vinegar off and let it dry completely.
Sterilize your sippy cups.
Make a diluted bleach solution.
Try a vinegar bath.
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