Pumping, Storing, Cleaning, and Thawing: What you need to know about handling breast milk

A quick guide to keeping pumped milk clean, safe, and ready for the babies who need it most

At Mothers’ Milk Bank, we provide carefully screened milk for medically fragile infants in the NICU. Every donation is tested for bacteria, pasteurized, and stored at regulated temperatures in full accordance with HMBANA guidelines to ensure safety and quality. Whether you’re feeding your own baby or sharing your surplus with others, the proper handling of human milk is critical to ensuring its overall safety and shelf life.

As you begin your pumping or breastfeeding journey, there’s a lot to know about cleaning pump parts, storing your milk, and thawing it for your baby. Germs can grow quickly in breast milk or breast milk residue that stays on your pump parts long after you use them. It can be confusing to stay on top of all the information out there, but here are the most important do’s and don’ts, according to the Centers for Disease Control and Prevention (CDC):

---

Cleaning pump parts

The CDC released new guidelines in 2024 to ensure that all parts of the breast pump that come into contact with milk are cleaned. Germs can grow quickly in breast milk, and it’s important to make sure precautions are taken.

Before each use:

• Wash your hands well (with soap and water!) for 20 seconds.
• Wipe down the countertop where your pump and bottles will be placed during your pumping sessions (disinfectant wipes work great for this). 
• Assemble the clean pump kit. If you spot any mold in the tubing, discard and replace it right away.

After each use:

• Once you’ve stored your milk safely (don’t forget to label it with the date and time!), clean the pumping area. Wipe the countertop down, and clean the dials and power switch of the pump. 
• Take the pump apart. Separate all the parts that come in contact with your breasts or milk, such as flanges, valves, membranes, connectors, and milk collection bottles.
• Rinse all pump parts that come into contact with your breasts or milk. You can also clean your pump parts in a dishwasher, but check your user manual just to be sure.
• Before you finish up, clean the bottle brush and/or wash basin if you used one. 
• Air dry everything.

---

Storing breast milk

These guidelines are for healthy full-term babies and may vary for premature or sick babies. Check with your health care provider.

To store expressed breast milk, use designated breast milk storage bags or clean, food-grade containers made of glass or BPA-free plastic) with tight-fitting lids to store expressed breast milk.

According to the CDC, freshly expressed or pumped milk can be stored:

• At room temperature (77°F or colder) for up to four hours
• In the refrigerator for up to four days
• In the freezer for about six months (six months is best, but up to 12 months is acceptable.)

The CDC created this handy printable to stick on your refrigerator as a gentle reminder for yourself, your partner, or anyone caring for your baby.

Some extra tips:

• Label all milk with the last date expressed before storing. Add your baby’s name to the label if there’s a chance that the milk may be given to your baby in a daycare or preschool setting.
• To avoid waste as your baby’s needs change, store milk in different amounts ranging from one to four ounces.

---

Thawing breast milk

Breast milk should not be treated in the same way as other frozen foods when it comes to thawing and preparing it for consumption. Here are some guidelines from the CDC to ensure you’re thawing safely:

• Remember the “FIFO” rule: First in, first out. Always thaw the oldest milk first.
• There are three appropriate ways to thaw milk: under lukewarm running water, in a container of lukewarm water, or in the refrigerator overnight (for about 12 hours).
• Never thaw milk in the microwave or on the stove. The microwave can destroy your milk’s nutrients and create hot spots, which can burn a baby’s mouth.
• If thawed in the refrigerator, use thawed milk within 24 hours of it being completely thawed. For example, if you put it in the refrigerator at 7:00 pm, let it thaw until 7:00 am and use it before 7:00 am the following day.
• If thawed in water, use milk within two hours of bringing it to room temperature.
• Never refreeze thawed milk.

We understand the challenges that can come with breastfeeding during an already busy and overwhelming time, and are here to help you navigate them every step of the way. For more information, resources, and support for breastfeeding, click here or reach out to us directly.