Breast milk may be stored in a freezer for up to three months and in a deep freeze for up to 12 months. The freezer is cold enough if it keeps your ice cream solid. That will be about 0° degrees F (-20°degrees C). It should be placed in a part of the freezer that will not be subject to changes in temperature as the door is opened and closed. If plastic breast milk storage bags are used, they should be doubled or protected from being bumped and torn in the freezer.