It is not recommended to do so as you might unintentionally damage the vacuum seal, causing it to lose its insulating properties and not able to keep your beverages temperature as long. Our products are double wall vacuum insulated, beverages in our products will be protected from the temperature inside the freezer and wouldn’t be able to freeze. If you want ice cold water, put some ice cubes inside your bottles or cups and notice how long it takes them to melt!