This depends entirely on the brand that you purchase. “Most breastmilk storage bags are disposable and not meant to be reused,” DeWeese says. “However, there are some brands that are specifically made to be reused, including those made from thicker, stronger plastic or silicone materials.”  You should look closely at the manufacturer’s information to determine whether or not the bags are reusable. And  if they are, DeWeese notes that even those can only be used a certain number of times before they need to be replaced. Some options are even recyclable so you can feel better about single-use bags.