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Milk Storage

Dos and Don'ts of Storing Breast Milk

Dos and Don'ts of Storing Breast Milk

by: Andrea Tincher, Pasteurization Tech, IMMB

Dos & Dont's of Storing Breastmilk {}


  • DO include first and last name of mom or baby, date (mm/dd/yy) milk was pumped, and donor number if known. Estimated number of ounces is always a bonus!
  • DO be sure to fill bags only to the maximum amount listed on the bag! 5 ounces is preferred.
  • DO store bags as flat as possible in your freezer. TIP: Store bags in a plastic storage bin, shoe box or another container in your freezer. Some moms even use a separate container to store milk in order by earliest date frozen.
  • DO be sure to remover any excess air before zipping the bag closed.
  • DO be sure to zip your bags and double check they are completely sealed- this is important!
  • DO keep a permanent marker in your pumping bag and mark the storage bags as they are filled. We know sleep deprivation is a real thing and we want to make sure your milk is accurately labeled and dated.


  • DON'T store bags on their side, tightly against other items, or against the freezer door.
  • DON'T overfill the storage bag! Please only fill the bag to its maximum capacity.
  • DON'T forget to double check that you have labeled your bags before donating.
  • DON'T overlook general hygiene, hand washing, and sanitizing your pumping parts.

Dos & Don'ts of Storing Breastmilk {}


When milk storage bags leak not only is milk lost in volume but the composition of the milk is changed such as fat, protein, and nutritional content.

If your bag has a hole or is not sealed properly it is possible for germs and bacteria to get into the milk.

As milk freezes, it expands…a lot!  Bags that are too full will most likely burst at the seams or tear.

We highly value you as a donor and want you to be confident that all of your milk is being used.  These guidelines not only help us but will also help you know that your own baby is getting the best of your milk.  Properly storing it will ensure that we are able to use all of your milk to nourish the babies who need it most.

Please take special note: if your bags are not properly labeled we will be unable to use your milk.  Bags that are not labeled become a safety concern due to the volume of milk and number of donors we may receive at any given time.  The guessing game of “Who’s milk is this?” is not a risk we are willing to take when it comes to feeding our fragile babies.