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After you’ve used your breast pump you’ll need to store the expressed breast milk until your baby needs it. There are a few different storage options to choose from, which will ultimately come down to your family situation and personal preferences. This article will discuss with you the four most important aspects of storing breast milk:

  • Where to store
  • How long to store
  • What container to use
  • Handling and thawing FAQ

Let’s not waste any more time and delve into the ins and outs of how to store breast milk.

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Storing breast milk | How to store your breast milk. Tips for pumping moms. Stork Mama

Where to Store your Breast Milk

There are four different options you have when choosing where you should store your breast milk. Your choice will depend on how quickly you want to use the milk or the reason for expressing.

Room Temperature

Best For: Recommended if you want to use fresh expressed milk within a few hours.

Best Storage Practice: Due to its anti-bacterial properties, breast milk is safe in room temperature for around 3-8hrs depending on how hot or cool the room is. Avoid as much heat as possible, place the milk in a cool dark area of the room. If this is not possible a damp towel can keep the bottle cooled for longer.

Cool Box

Best For: Recommended if you want to use the milk in the next 4-24hours. Great option for working moms.

Best Storage Practice: A small ice pack cooler helps act as a convenient transport method while keeping the milk fresh. For best practice use an icepack with close contact to the milk and keep opening to a minimum.


Best For: Short term breast milk stash which will be used within 8 days.

Best Storage Practice: Milk is kept fresh, without the risk of losing nutrients and the hassle of thawing frozen milk. Use the milk within 3 days (72hours) of expressing as the risk of bacterial contamination increases the longer the milk is stored. Place the milk in the middle of the fridge at the back, as this is the coolest spot. Avoid storing in the door as frequent opening causes temperature fluctuation.


Best For: Long term storage option if you plan to use pumped milk anywhere from 2 weeks up to 6 months after expressing. Great for if you plan to express and keep a large breast milk stash.

Best Storage Practice:  The maximum  length of time you can store for will will depend on the lowest temperature your freezer can achieve and how often the freezer door is opened. Store in the coldest part of the freezer, at the back, away from the sides and the door where the temperature is most constant.

How Long Does Breast Milk Last?

It’s important to know how long to store your breast milk for to ensure freshness and prevent bacterial contamination. We’ve come up with this handy chart to remind you of safe storage times for breast milk. Feel free to print it off and stick it on your fridge for quick reference.

The information in the table applies to expressing moms who:

  • Have a healthy term baby
  • Are storing for home use
  • Maintain hand hygiene when expressing and handling milk
  • Sterilize pumping and storage containers before use

Guidelines may vary if your baby is sick or premature and required milk stored for hospital use. We recommend you discuss breast milk storage policies and guidelines with your baby’s hospital. This also applies to donated breast milk for hospital use.

Choice of Breast Milk Storage Containers

You’re probably now wondering what you should use to store the breast milk in. The best storage container for your baby will depend on where you are storing the breast milk and how often you intend to express. Let’s explore your options.


This is the best option for moms planning to express infrequently and storing the milk at room temperature, in a cool box or in the fridge.

Advantages of Bottle Storage

  • Convenience
  • Hygiene
  • Less washing
  • Durable

Disadvantages of Bottle Storage

  • Bulky

Baby Bottle Materials

Plastic: Easy to use and durable, best for infrequent expressing and short term storage (2-72 hours) as the plastic can start to cling to nutrient after this time Freezer friendly but takes up a lot of room.

Glass: Great for fridge storage at all times, will not leech chemicals into the breast milk, careful storage required to ensure falls are prevented. Freezer friendly (must be defrosted slowly).

Stainless Steel: Another non plastic alternative, great for fridge storage at any time and will not break, anti-bacterial materials. Not suitable for freezer use.

Breast Milk Storage Bags

Storage bags are the best option freezer storage, although they can also be used for fridge storage. Some breast milk storage bags are designed so you can express directly into them, store and then decant to a feeding bottle once thawed. These bags are not reusable so if you are pumping long term factor in the cost of repurchasing these, buying in bulk will save money. Check out our reviews of the best storage bags for breast milk here.

Advantages of breast milk storage bags

  • Convenience
  • Space saving
  • Hygiene

Disadvantages of breast milk storage bags

  • Increased waste
  • Single use
  • Risk of leaking

Breast Milk Storage Trays

Like ice cube trays but for your breast milk, this a great space saving option for moms who want to have portion control for baby to minimize waste. They are filled and sealed with a lid to prevent freezer burn. When needed a portion is removed and placed into a feeding bottle and defrosted.

Advantages of breast milk storage Trays

  • Ideal for small volumes of milk (usually in 1oz cubes)
  • Reduce waste
  • Quick thawing
  • Use for weaning foods

Disadvantages of breast milk storage trays

  • Freezer use only
  • Increased handling
  • Can pump directly into

Another freezer tray tip is to freeze a tray of cubes them transfer to a food safe freezer bag, so you can refill a new batch in your tray. If you do this remember to keep each batch separated and labelled to ensure the oldest batches are used first.

Read: Best Breast Milk Storage Bags When Expressing

Organizing Your Stored Breast Milk

If you plan to build a stash of breast milk by expressing on a regular basis you will need to bring some order to all that milk. By organizing you milk stash you ensure your baby receives the oldest milk first so that milk doesn’t go ‘off’. It will also help you to save space in your fridge or freezer, for other non-milky goods.


You should get into the habit of labeling your containers with the date after expression. This ensures you use the milk in the order it was expressed. If you are planning to use the milk in an area where more than one baby has milk stored (e.g. hospital or day care) them remember to write you baby’s name on it.

Bottles can be dated with sticky labels or with labeling lids. Breast milk storage bags usually prove labellings areas to prevent puncturing the bag. It’s best to label with a permanent waterproof pen so the ink stays in place when storing or thawing.

Storage organizer

You can purchase plastic organizers which keep your breast milk storage containers in order, and away from other fridge and freezer items.

Bottle organizers: Keep bottles upright with a crate design. These are ideal especially for glass baby bottles to minimize risk of damage to the bottles.

Storage bags organizers: Keeps the bags stored upright or flat to save space. They are often box shaped or lidded to provide extra protection for the storage bags and prevent freezer burn. If there is any mess from a leaking bag it is often contained within the container.


Labeling will help you to manually rotate your stash of milk, however you can also buy a rotational unit which uses as first in and first out system. These systems are sturdy and save space in your fridge or freezer.

Look out for special features such as ones for breast milk bags which have a freezing plate on top. These allows you to freeze flat and prevent storage bags sticking to other bags in the process.

Handling and Thawing Breast Milk FAQ

My breast milk looks watery

Your breast milk is made up of a watery fore milk and a creamy hind milk. When the milk cools in storage its common for these to separate with a cream top and thin bottom. This is normal and easily fixed by gently swirling together before heating. Don’t be tempted to shake the milk as it can destroy the nutrients.

What color is breast milk?

It’s not uncommon for breast milk to take on a blue, yellow, green, or brown hue. The main cause is often mom’s diet or medications. A different color doesn’t mean the milk if unusable, unless the milk smells sour.

My thawed breast milk smells rancid

If you have frozen milk and then thawed only to find it’s usually one of three causes: incorrect storage, long term storage or high lipase volumes in your milk. If you produce too much lipase in your milk it will break down the fats in the milk, particularly when frozen. You cannot treat already rancid milk, and most babies will refuse to drink it.

The best way to test of you produce high lipase volumes is to freeze a test batch of expressed milk. If it does not always thaw with a rancid smell it’s likely that it’s a storage issue.

If your milk is high in lipase, you can scald the milk to prevent it happening with future batches. This means bubbling a pan of milk at the edge of a pan (not boiling) to deactivate the enzyme. Cool the milk and store in the freezer as usual.

Can you mix breast milk from different days?

If you have expressed milk at different times of the day it’s safe to mix the milk under certain conditions. The oldest milk needs to have been stored in a refrigerator (32-60⁰F or 0-15⁰C) and expressed within the last 24 hours.

It’s possible to mix refrigerated milk up to 8 days old with freshly expressed milk, as long as you cool the fresh milk first. You can re-refrigerate the milk again up to the maximum storage time of the oldest milk. For example if you mix 3 day old milk with fresh breast milk, you can store the mixed milk in the fridge again for 5 more days before discarding. You can also freeze the milk and label with the date the first milk was expressed.

Can you mix frozen and fresh breast milk?

Fresh breast milk can be mixed with frozen milk is the fresh breast milk is cooled first and the volume is less than the frozen milk. Best practice is to thaw the frozen milk first and allow the fresh to cool for around 30 minutes and then mix.

You can refrigerate the mixed milk for up to 24 hours after thawing. Do not refreeze thawed breast milk.

Can you mix breast milk and formula?

There are no implication to mixing fresh breast and formula milk, however we don’t advise it. If you plan to supplement baby we suggest feeding baby the expressed breast milk first. This ensure they fill up mostly on breast milk and receive the higher quality calories and nutrients. If baby still needs more then mix a fresh batch of formula. This method will endure breast milk waste is kept to a minimum.

How to thaw frozen breast milk

The best way to thaw frozen breast milk is to place the container in a refrigerator for 12 hours. It’s best to thaw breast milk slowly to prevent destroying the nutrients. We do not recommend leaving breast milk at room temperature as it can be vulnerable to bacterial growth and uneven thawing.

To thaw frozen breast milk in a bottle or storage bag slowly run under a cool tap, gradually warming the temperature until the milk thaws and reached room temperature. You can also place the container in a bowl of luke warmer water and leave to thaw.

For convenience you can use a specialist bottle or bag warmers which have defrost features for frozen milk. Check out our article on the best baby bottle warmers.

Never thaw or heat your baby’s milk in a microwave. Not only will it destroy the vitamins but can create heat pockets which can scald your baby’s mouth.

How much breast milk should I thaw?

A good tip to allow milk to thaw quickly is to store in smaller quantities of around 2oz-4oz. Take out only what your baby need for a feed and this helps to reduce breast milk waste.

Storing breast milk at work

If you are storing breast milk in a communal fridge at work you are not required to store it separately or with special equipment. In this instance breast milk is treated as a food stuff rather than a body fluid. We recommend using an icepack cooler to stored expressed breast milk at work to minimize temperature fluctuations from frequent opening. A cooler bag also makes it easier to travel home with your expressed milk.