How to Effectively Use Breastmilk Storage Bags - bökee

How to Effectively Use Breastmilk Storage Bags

If you plan to pump breastmilk, chances are you plan to freeze some of it for future use. Though you can use freezer-safe baby bottles for storage, this is neither the most economical or space-saving choice. Breastmilk storage bags are your best option.

Learning how to use breastmilk storage bags correctly will save you a lot of trial and error when it comes time to do so. Here we’ll talk about your breastmilk storage bag options as well as the steps you need to take to use them for successful and safe breastmilk storing.

Types of Breastmilk Storage Bags

There are two main types of breastmilk storage bags: disposable and reusable. Here's what to expect with each type.

Disposable Storage Bags

Disposable bags are a time-saving option. Since they’re only suitable for one-time use, there is no cleaning involved.

Disposable breastmilk storage bag features:

  • Suitable for one use only
  • BPA-free
  • Come pre-sterilized
  • Graduation lines make it easy to measure your milk
  • Most have a designated space to write the number of ounces as well as the pumping date

Because disposable bags are made from a thin plastic, they take up less space than reusable bags, which is something important to consider if you know you’re going to need to store a lot.

Reusable Storage Bags

If you are looking for the environmentally-friendly choice, you can choose to use reusable breastmilk storage bags. 

Reusable breastmilk storage bag features:

  • Made from food-grade silicone
  • BPA-free
  • Can be sterilized in the same manner as baby bottles and pump parts
  • Highly durable means they won’t leak
  • Graduation lines (though these are a bit tougher to see than on disposable bags)
  • Eco-friendly

Junobie reusable bags and the bökee make a great combo!


Reusable storage bags are likely not the most economical option if you are building up a large freezer stash of milk. But if you have a small freezer stash that you rotate through fairly frequently, reusable bags are a great option that you can feel good about using.

Steps for Using Breastmilk Storage Bags

Just pour the milk in and freeze, right? Well, it's not TOO hard of a process, but it's a bit more involved than that. And we promise you're going to want to read on as we'll give you our best tips for pouring and storing as well as give you the guidelines you need to know to safely freeze and thaw that precious liquid gold.

Step 1: Fill Using One of Two Methods

Depending on the breast pump that you are using as well as which storage bags you are using, you may be able to pump directly into storage bags. The Pump and Save bags from Medela  for example, are one type that have this capability (when used with the easy-connect adapter). The other option is to pump into bottles and then fill your storage bags with the ideal amount of breast milk.

Pump Directly into Storage Bags

Pumping into storage bags can definitely be a time-saver. It will allow you to skip the extra step of pouring between containers before freezing.

However, a downside to this method is not being able to adjust the milk you freeze in one container as easily. For example, if you pump 3 ounces on each breast, but want to freeze your milk in 5-ounce portions, this won’t work. It’s pretty difficult to pour from one storage bag to another, so it’s better to use bottles if you’re going to need to combine milk before freezing.

Pump into Bottle and Then Transfer to Storage Bags

This method will require pouring from bottle to bag, but the advantage is that it allows you to customize how much milk you put into each bag. I always found it helpful to freeze full servings as well as “top-off” servings in 2-ounce portions.

Though this does require one more step, it’s worth it because you’ll likely end up wasting less milk. And it’s just nice knowing you have exactly the amount of milk you need for your baby’s feeding. Prep this way is made easy when you transfer using the bökee.

The bökee is a one-handed bottle prep accessory that is a great tool for filling breastmilk storage bags. Normally it would be impossible to prep your breastmilk storage bags while holding your baby, but the bökee makes it doable...without the risk of any spilling. To use the bökee in this way we suggest the following:

  • Place bag in bökee and open fully with your hand
  • Place flange inside to use as a funnel
  • Pour bottle of milk to correct graduated line

RELATED: Best Baby Bottle Accessories of 2020

Even if you don’t need to complete this process one-handed, the bökee is a great stabilizer for your breastmilk bags to ensure they don’t tip over. Because that is a scary thought!

Step 2: Store in a Space-Saving Manner

Once you have filled your breastmilk storage bag, it’s time to seal and store. Here’s what you’ll want to do:

  • Ensure you have filled the bag to the correct graduated line. Double check that the bottom of your bag is flat, otherwise it will look like you have more than you do. 
  • Push out all air from the bag which will help with space-saving as well as prevent air bubbles within the breastmilk.
  • Seal tightly to ensure there is no possibility for leaks.
  • Use a permanent marker to write the date and number of ounces on the bag. This is an important step because it allows you to ensure you’re using your breastmilk in a safe time frame and you won’t be abe to tell the correct number of ounces once it’s frozen.
  • Lay flat and place into the freezer.

Keeping your breastmilk storage bag flat in the freezing process is ideal for space-saving. Once frozen, you can either keep them laid down, or stand them upright in a container. Standing upright in a container makes it easy to bring the oldest bags to the front so that you can use those first.

Step 3: Thaw Safely

When it’s time to feed your baby from your frozen stash, you’ll want to make sure that you follow safe thawing guidelines to ensure you’re giving bacteria-free milk to your baby.

  • Use your oldest breastmilk first. 
  • Thaw by placing the breastmilk storage bag in the refrigerator. If you don’t have time to wait for the milk to thaw in the fridge, you can thaw it in a bowl of warm water or by holding it under warm running water. (Do not thaw frozen breastmilk out of the fridge at room temperature!)
  • Once thawed, transfer the milk to your baby’s bottle - you can do this one-handed using the bökee.
  • Use a bottle warmer such as the Baby’s Brew to safely warm your baby’s bottle to the desired temperature.

Congrats - you’ve completed the process of pumping, freezing, and transferring your baby’s breast milk and it’s time to feed your little one. You are one amazing mama!

A couple more things to note on the thawing process:

  • Frozen milk should be used within 6 months, with closer to 4 months being ideal
  • Milk that’s thawed in the refrigerator needs to be used within 24 hours. According to the CDC: “This means from the time it is no longer frozen or completely thawed, not from the time when you took it out of the freezer.”
  • Never refreeze milk once it has been defrosted.

Step 4: Discard the Bag

Unless you are using a reusable storage bag such as the ones from Junobie, your disposable breastmilk storage bag needs to be thrown away. These are intended for one-time use, so it is not a safe practice to reuse them.

FAQ about Breastmilk Storage Bags

These are some of the most frequent questions we get asked about using breastmilk storage bags.

Can you wash and reuse breast milk storage bags?

Disposable storage bags like those from Medela or Lansinoh should only be used once. Out of the box these types of storage bags come pre-sterilized, but after use, they are no longer sanitized and should be thrown away. 

However, you can now find reusable breast milk storage bags made from silicone and these are perfectly safe to reuse when cleaning and sterilizing properly between uses. Be sure to follow the instructions given by the particular manufacturer, but generally these can be washed in the sink with hot water and soap or in the top rack of the dishwasher. You can also sanitize them using a baby bottle sanitizer, such as these.

Can you use sandwich bags to store breast milk?

Using sandwich bags to store breastmilk is not advised. For one, you can’t be confident in their sterilization and that they will keep your breastmilk free of bacteria. Additionally, they will most likely break if you try to freeze them.

Should I remove air from breastmilk storage bags?

Squeezing out the air from the top of a storage bag before sealing tightly will allow for easier, space-saving storage. This also helps to prevent air bubbles from forming within the milk.

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