Storing Your Breastmilk: Guidelines, Tips, & Tricks

Whether you need to build a stash of breast milk before returning to work, or just want to keep some expressed milk on hand for the occasional date night, storing that “liquid gold” can be done easily and safely by following just a few guidelines. Read on for storage guidelines as well as some handy tips and tricks.

Expressing & Storage

  • Always begin with clean hands and a pump cleaned in hot, soapy water.
  • For short-term storing, such as in the refrigerator, you can keep the milk in the plastic bottle that comes with your pump or transfer it to bottles measured for individual feedings. Some controversy exists as to whether you should use glass or plastic bottles. Immunological cells in the milk are purported to stick to the sides of glass bottles, however the difference is probably negligible if your baby is receiving only some of his milk from bottles. If your baby is exclusively fed pumped milk, you may wish to use both plastic and glass.
  • If you’re pumping at work, you can store your milk in a travel cooler with ice packs or in a common space refrigerator. Although a bodily fluid, breast milk is not considered a biohazard and the CDC does not require special handling, labeling, or separate refrigeration (1).
  • Milk that you plan to use within 8 days should be kept refrigerated, as opposed to frozen, so that thawing is not necessary.

  • For long-term storing, you can use glass or plastic containers, or plastic freezer bags made specifically for storing breast milk. Some plastic milk storage bags attach directly to a pump for easy handling. Breast milk storage bags are thicker and have a lining to prevent fatty components from sticking to the side. They usually also have a space for easy labeling as well as scales for measuring. Squeeze out extra air and be sure to leave room in the bag for expansion. Plastic bottle liners are not suitable and likely to leak.
  • If you need to combine freshly expressed milk with frozen milk, cool the expressed milk first. Don’t add more than there is of the frozen, since you want to avoid the frozen milk thawing.
  • Lastly, don’t forget to label the bag with the date! If you combine milk from several pumping sessions, label it with the date of the oldest milk.

Guidelines for Storage

The following are the accepted guidelines for safe storage of breast milk. Always store milk as far away from the door as possible, where temperatures may fluctuate.
Breastmilk Storage Guidelines
Room temperature (66-78°F):
4-6 hours
Cooler with frozen ice packs (59°F):
up to 24 hours
Fresh milk in refrigerator (≤39°F):
up to 8 days
Thawed milk in refrigerator (≤39°F):
up to 24 hours
Freezer unit:
up to 6 months
Deep freeze unit:
up to 12 months

Use & Handling

  • When you’re ready to use frozen milk, thaw in refrigerator (usually 12 hours or overnight) or run under lukewarm water if needed right away.
  • Swirl your bottle of milk gently before use if the creamier portion has separated, but do not shake! Shaking can cause important proteins in the milk to break apart (2).

  • If your baby does not finish a bottle, most sources say it is OK to re-refrigerate once (3). That is, to avoid waste you can put the milk back in the fridge and offer again within a few hours. After that, if your baby does not finish the milk, it should be discarded. As a precaution, it should not be kept longer since bacteria from the babies mouth has contaminated the nipple.
  • When you need milk from your supply, always use the oldest first. Don’t worry if the oldest is weeks or months old. It is true that the composition of your milk changes over time to suit your growing baby’s needs. However, even older milk, as long as it has been properly stored and handled, is beneficial to your little one.

Tips & Tricks

  • When freezing, store milk in smaller portions such as 1-3 ounces in order to avoid waste.
  • Store bags, tightly sealed, flat and stacked. This will speed thawing time.
  • You can get extra use out of your pump accessories between washings by giving them a quick rinse, throwing them in a large ziploc bag, and storing them in the refrigerator until the next pumping session.
  • What to do if your power goes out? Open the door as little as possible. Full freezers will hold their temperature for approximately 48 hours if the door is kept closed (4). You might also consider taking your supply to a nearby neighbor with power. If there are still ice crystals in the milk, you can consider it to still be frozen. Most experts do not recommend refreezing the milk, although there has been little research on how repeated re-freezing changes the properties of breast milk. If you know ahead of time of a potential long power outage, you might also consider packing your supply in dry ice.
  • Does your milk smell soapy? Most breast milk has a mild or slightly sweet scent, but mothers occasionally report that thawed milk smells soapy. This may be due to enzymes in the milk digesting some of the fat and is probably fine if your baby accepts the milk. If not, scalding (but not boiling) the milk and quickly cooling prior to freezing may solve this problem if baby is rejecting the milk, although this may lower the nutritive content and is not ideal (5).
  • If you and your baby experience thrush, you can still give milk pumped during the infection to your baby while being treated. After the infection has cleared, however, discard the milk as neither cooling nor freezing kills yeast (6).
  • Left some pumped milk out longer than the recommended guidelines? Instead of tossing the milk, consider using it for diaper rash, baby eczema, cradle cap, or any of a number of alternative uses.



Read more about breastfeeding in these posts from Daily Mom:
Returning to Work and Pumping
Breastfeeding During the Holidays
Breastmilk Pancake Recipe



  1. Center for Disease Control and Prevention: “Human Immunodeficiency Virus (HIV), and Acquired Immunodeficiency Virus (AIDS)“.
  2. Smith, Linda J. (1998) “Don’t Shake the Milk“. Bright Future Lactation Resource Center Ltd.
  3. The Academy of Breastfeeding Medicine Protocol Committee (2010). “ABM Clinical Protocol #8: Human Milk Storage Information for Home Use for Full-Term Infants (Original Protocol March 2004; Revision #1 March 2010)“. Breastfeeding Medicine, 5(3). doi: 10.1089/bfm.2010.9988
  4. USDA Food Safety and Inspection Service, US Department of Agriculture. “Keep Your Food Safe During Emergencies: Power Outages, Floods & Fires“.
  5. Kelly Mom, “My expressed breastmilk doesn’t smell fresh. What can I do?“. July 28, 2011.
  6. Le Leche League International. “What are the LLLI guidelines for storing my pumped milk?“.


This post is meant for educational purposes only. It is not intended to replace medical advice from your physician, doctor or health care professional. Please read our terms of use for more information.

Photo credits: The Whimsical Photographer, The Quintessential Mommy




We don’t spam! Read our privacy policy for more info.

Laura is a wife and a new mom living on the East Coast. She and her husband welcomed their first child in September 2013. She has a passion for photography and an incurable case of Wanderlust. In her spare time she enjoys blogging about photography, travel, married life, and motherhood at The Whimsical Photographer.

Boram Postnatal Retreat: A New Mom’s Must-Have Haven in Her 4th...

For nine long months, Mama, you carry your baby inside of you. Nesting instinct kicks in and you prepare a cozy space for their...