bamama is reader-supported. When you buy through links on our site, we may earn an affiliate commission. Learn more

How to Use Breast Milk Storage Bags – The Effective Way

How to Use Breast Milk Storage Bags – The Effective Way

Storing your breast milk after pumping is a fantastic approach to ensure your infant gets all the necessary nutrients, minerals, and vitamins. 

You can store your milk in food containers or baby bottles, but they’ll take up a lot of room in the refrigerator or freezer. 

The best method for preserving and storing breast milk is to use storage bags. They were made specifically for that function, after all. More importantly, they’re simple to use.

Having milk on hand is undeniably advantageous, particularly for mothers who must leave their children while working or attending to business.

I’ll discuss what you must remember when storing breastmilk, including the measures you must follow to use them successfully and safely.

Breast Milk Storage Bag Types

Breast Milk Storage Bag Types

Breastmilk storage bags come in two primary categories: disposable and reusable. Here’s what you need to know about each type.

Disposable Storage Bags

Using disposable bags can save time. There is no need to clean them because they can only be used once.

Features of Disposable Breast Milk Bags

  • One use
  • BPA-free
  • Arrive sterilized
  • Graduation lines make measuring your milk simple
  • Most have a space where you can record the number of ounces and the pumping date.

Disposable bags take up less room than reusable bags because they are thin plastic, which is something to keep in mind if you need to store a lot.

Reusable Storage Bags

Reusable breast milk storage bags are a great option if you want to save the environment. 

Features of Reusable Breast Milk Storage Bags

  • Made from silicone that is suitable for human consumption
  • BPA-free
  • Sterilized similarly to baby bottles and pump parts
  • Less prone to leaking
  • Graduation lines, but a little more difficult to see than on disposable bags
  • Eco-friendly

If you’re stockpiling a sizable freezer cache of milk, reusable storage bags probably aren’t the most cost-effective choice. 

Reusable bags, however, are a fantastic choice that you can feel good about using if you have a modest freezer supply that you rotate through regularly.

How to Pump Into Breast Milk Storage Bags

How to Pump Into Breast Milk Storage Bags

Storage bags are a simple, space-saving method to help your child benefit from your breast milk even when you’re away.

Undoubtedly, pumping into storage bags can save you time. It also bypasses the unnecessary step of pouring between containers before freezing.

The disadvantage of this method is that you can’t quickly change the amount of milk you freeze in a single container. 

It won’t work, for instance, if you express 3 ounces from each breast but want to store your milk in 5-ounce increments. 

If you need to combine milk before freezing, it’s advisable to use bottles because pouring from one storage bag to another can be challenging.

Here’s how to pump breast milk straight into storage bags:

  1. Before pumping or manually expressing, wash your hands with soap to ensure that the breast milk your baby drinks is secure and clean. Make sure your breast pump is clean throughout.
  2. Open the breastmilk storage bag by removing the tamper-proof safety seal and pulling the zipper seal apart.
  3. Insert the expression set. Tilt the expression set. Align the expression set below the zipper seal when you insert it. Pull the bag’s opposite side gently over the expression set so the clear zipper is over it on all sides. 
  4. When the expression set is just below the clear bottom zipper around the bag, gently pull the bag down. To verify that the bag is closed, gently tug on the bottom.
  5. Repeat steps 2-4 if using a double pump.
  6. Pump as usual.
  7. Reverse step 3 to remove the bag. DO NOT PULL THE BAG DOWN DIRECTLY.
  8. Holding the bag firmly in place, gently push the zipper seal past the expression set. Holding the bag firmly, tip it to the side, and remove the adapter.
  9. Lock the bag. For future reference, note the date, time, and amount of breastmilk on the label.

How to Store Breast Milk in Storage Bags

How to Store Breast Milk in Storage Bags

You shouldn’t cry over spilled milk, but that saying doesn’t apply to breast milk.

You worked hard to pump it, and you should store it properly! All parents should follow these general recommendations for breast milk storage.

Wash Those Hands

To properly clean your hands, use soap and water. If you can’t access soap and water, use a sanitizer that contains at least 60% alcohol.

Stick to Small Batches

Breast milk shouldn’t be reheated or refrozen once defrosted, much like other foods. 

Store leftover milk in tiny batches of 2 to 4 ounces and label them with the date they were expressed to prevent wastage. 

It minimizes the possibility of waste while making it simple to reheat additional milk if your infant’s still hungry. 

Additionally, the CDC advises immediately freezing newly expressed breast milk to preserve quality if you believe your baby won’t consume any within four days.

Store With Space-Saving Techniques

Now it’s time to seal and store your breastmilk storage bag after you’ve filled it. Here’s what you ought to do:

  • Make sure the bag is filled to the appropriate graded line. Ensure your bag’s bottom is flat; otherwise, you will appear to have more milk than you do. 
  • Remove all air from the bag to maximize storage and avoid air bubbles in the breast milk.
  • To ensure that there are no leaks, securely seal the container.
  • Write the date and ounces on the bag using a permanent marker. This is crucial since it allows you to ensure you’re using your breast milk within a safe time limit and because after it’s frozen, you won’t be able to determine the exact number of ounces.
  • Place the flattened bag in the freezer.

It’s best to freeze your breastmilk storage bag flat to maximize storage capacity. When frozen, you can store them flat or upright in a container. 

When they’re upright in a container, moving the oldest bags to the front is simple so you can utilize those first.

First In, First Out

Always keep in mind that first in, first out. First, defrost the oldest breast milk. The quality of breast milk can deteriorate over time.

Thaw Safely

When feeding your baby from your frozen supply, follow safe thawing instructions to keep your infant’s milk bacteria-free.

  • Use the oldest milk first.
  • Place the breastmilk storage bag in the fridge to defrost. If you can’t wait for the milk to thaw in the fridge, thaw it by holding it under warm running water or in a dish. (Do not thaw frozen breast milk out of the fridge at room temperature.)
  • Transfer the milk to your baby’s bottle once it‘s thawed.
  • Use a bottle warmer to securely warm up breast milk to the correct temperature.

It’s time to feed your child after you’ve finished pumping, freezing, and transferring your baby’s breast milk. You are one incredible mother! Two additional points about the thawing procedure:

  • Use frozen milk within six months or four months, ideally.
  • Milk thawed in the refrigerator must be consumed within 24 hours. It means when it is no longer frozen or completely thawed, not when you take it out of the freezer.
  • Milk that’s been defrosted once should never be refrozen.

Throw Away the Bag

Your disposable breastfeeding storage bag must be discarded without using a reusable storage bag. Reusing them is unsafe because they’re only meant to be used once.

Ziploc for Breast Milk

The container you choose to store your breast milk in matters. 

Use spotless glass or hard plastic containers instead of those made with bisphenol A (BPA). A plastic liner made for breast milk can also be used. 

Using Ziploc bags is not advised since they can leak. Put breast milk in the back of the refrigerator or freezer, where it will stay colder, before packaging it for storage.

What to Write on Breast Milk Storage Bags

On the storage container, note the date. If your infant attends a group daycare, also write their name on the label. 

Make sure to label it with your name or place it in a bag (also marked) if you are pumping and storing breastmilk in a shared refrigerator at work so it isn’t mistaken for regular milk.

Refrigerating Breast Milk Storage Bags

Refrigerating Breast Milk Storage Bags

Use the freezer for long-term breast milk storage and the refrigerator for short-term breast milk storage. It’s important to designate space in your refrigerator to store breast milk. 

Placing newly pumped milk in the coldest part of the refrigerator at the back center is advised. 

Breast milk should never be kept in the refrigerator door because the temperature changes when the door is opened or closed.

How Long Will They Last?

Breast milk storage can be refrigerated for up to four days. 

How About Room Temperature?

Generally, breast milk should only be left at room temperature for four hours after being freshly pumped and unopened. Discard it if it’s been more than four hours. 

Put the milk in the refrigerator if your baby hasn’t yet tasted it and you know you won’t use it during that period.

How About in an Insulated Cooler?

Breast milk can be transported safely for up to 24 hours in an insulated cooler with ice packs if you need to bring a bottle or bag while traveling.

How About in the Freezer?

Breast milk remains safe for three to six months when kept in the freezer. The milk must be kept at the rear of the freezer.

Breast milk can be safely stored using any abovementioned ways—freezing, cooling, or storing at room temperature for four hours. 

There are a few slight nutritional differences to be aware of, though. Freshly pumped breast milk is the most nutritious, but it will degrade quickly. 

At the same time, breast milk that has been refrigerated tends to lose less fat and retain more protective properties than milk that has been frozen. 

There are still benefits to keeping breast milk in the refrigerator or freezer, so it doesn’t mean one method is superior. You must act in a way that benefits your circumstances.

Why Does Fresh Breast Milk Differ From Thawed Milk in Appearance and Smell?

Why Does Fresh Breast Milk Differ From Thawed Milk in Appearance and Smell

Don’t worry, mommies! That’s normal. This occurs when mothers give birth to breast milk containing many lipase enzymes. 

This enzyme aids in the breakdown of fat found in breast milk and can also change the flavor and aroma of fresh and frozen milk (usually imparting a metallic or soapy flavor).

You probably won’t notice the changes in fresh milk because they take a few hours or perhaps a day to occur in the milk. 

Because of this, women frequently freeze their breast milk before realizing it contains a lot of lipases.  

Ask your doctor about a procedure to help neutralize the enzyme and minimize the scent if your baby doesn’t want to drink breast milk.

Can You Reuse Breast Milk Storage Bags?

Can You Reuse Breast Milk Storage Bags

To avoid contaminating your baby’s subsequent feeding, health professionals advise that you only use them once before discarding them. 

Thankfully, many breast milk storage bag packs are available in practical 25, 50, and 100-bag quantities, giving you enough to start a milk stash and feed your child while you’re away.

You can read a full guide on whether you can reuse breast milk storage bags here.

Frequently Asked Questions

Learn more about using breastmilk storage bags here.

How Long Do Breast Milk Storage Bags Last?

As long as they are kept in a cool, dry location away from moisture and oxygen, unopened breastmilk storage bags don’t lose their potency and keep for as long as they are stored. 

Most milk storage bags have been sanitized before use, making them safe. It indicates that they don’t need to be washed before usage. 

The same goes for these bags; once you’ve used them up, throw them away. Therefore, discard your milk storage bags once you’re done with them.

What Does Spoiled Milk Taste Like?

Milk gets a bad, rotten smell when it starts to deteriorate. Ignoring the smell is difficult, and it gets stronger over time. 

The natural sweetness of fresh milk quickly gives way to an acidic or sour flavor.

Can I Freeze Breast Milk Storage Bags?

Yes. There are freezer bags specifically made for storing breast milk. You can also freeze breast milk using storage bags.

It’s crucial to get bags made specifically for freezing extracted breast milk. This storage option has the greatest chance of leaking out of the three, so don’t overfill your bags!


Storing breast milk is a great way to guarantee that you can feed your baby later. It’s also a fantastic alternative for mothers who work.

Expressing and pumping milk to feed your baby requires much effort, time, and energy. You’ll need the best breast milk storage bags to avoid a disastrous spill or leak.

The best part is that these storage bags can be laid flat in the refrigerator, separated from one another by a sheet of kitchen paper.

Don’t worry, mommies; you’ll quickly get the hang of correctly preserving breast milk, though there may be a little learning curve.

Nayna Llenos
Nayna Llenos

Hi, I’m Nayna!
I’ve always wanted to be a mother, and I’m lucky and blessed to have two wonderful children to care for and love.
Despite this blessing, there are times wherein I do wonder if I truly am the mother my children need. Am I giving them the right food, care, and discipline to them?
But that is the beauty of parenting — you grow along with your children as they flourish to be their wonderful selves!
I wish to share my experiences with motherhood and how these tips can help you in your parenting journey.
I hope my advices and experiences will prove useful to you and that you have a smooth and wonderful journey as a mother!