After sterilizing your breast pump parts, store them fully dry in a clean, enclosed space like a closed kitchen cabinet dedicated to clean items. The key rule: parts must be completely air-dried before they go into storage, because even small amounts of trapped moisture can invite bacteria and mold growth.
Why Drying Matters More Than You Think
Sterilizing your pump parts kills bacteria, but storing them while still damp undoes much of that work. Moisture creates the exact environment where germs and mold thrive. The CDC is specific on this point: after sanitizing, place items on a clean, unused dish towel or paper towel in an area protected from dirt and dust, and let them air-dry thoroughly before storing.
The emphasis on “air-dry” is intentional. You should not rub or pat parts dry with a dish towel, even a freshly laundered one. Cloth towels can harbor bacteria that transfer right back onto your just-sterilized parts. If you’re short on time and parts still have water droplets, a clean paper towel is a reasonable compromise for gently dabbing off excess moisture. But air-drying on a clean surface remains the gold standard.
Where to Store Dried Parts
Once everything is fully dry, wash your hands with soap and water before touching the parts again. Reassemble the bottles and flanges completely, then place them in a clean, protected area. The CDC recommends a closed kitchen cabinet used only for storing clean dishes. The goal is keeping parts away from dust, cooking splatter, pet hair, and anything else floating around your kitchen.
Some practical options that work well:
- A dedicated cabinet or shelf: This is the simplest approach. Reserve one spot that stays clean and closed.
- A clean, covered container: A large food-storage container with a lid works if cabinet space is tight. Just make sure the container itself is clean and dry.
- A UV sterilizer with storage mode: Some sterilizer units, like the Tommee Tippee Ultra UV, have a storage mode that automatically runs a short sterilization and drying cycle every two hours. Parts stay sterile inside the unit as long as it remains plugged in and the storage mode is active. This is a hands-off option if you’ve invested in one of these devices.
Wherever you store your parts, the space should be enclosed. Leaving reassembled parts on an open drying rack or countertop exposes them to airborne contaminants between uses.
The Fridge Storage Shortcut
You’ve probably heard about putting pump parts in a bag in the fridge between sessions instead of washing every time. This is not the same as storing sterilized parts, and it’s worth understanding the difference. The CDC and most pump manufacturers recommend cleaning parts after every use. Refrigeration slows bacterial growth but does not stop it entirely.
The risk is that bacteria on unwashed parts can transfer to your breast milk at the next pumping session. Breast milk is nutrient-rich, which makes it an ideal environment for those bacteria to multiply. For most healthy, full-term babies older than a few months, this is probably a low risk. But it is still a risk, and it increases the longer you go between washes. If you do use this shortcut, place the parts in a clean, sealed bag rather than leaving them uncovered on a fridge shelf. And recognize that this is a convenience trade-off, not a recommended practice.
Stricter Rules for Premature or Vulnerable Babies
If your baby is in the NICU or has a compromised immune system, the standards are tighter. Babies in intensive care are more prone to infections, so hospitals typically require hand washing with soap and water before touching any pump parts, your breasts, or expressed milk. The fridge storage shortcut is not appropriate in this situation.
For NICU families, sterilizing parts before every use (not just cleaning) is often the expectation. Storage should follow the same principles: fully dry, fully reassembled, in a clean enclosed space. If your hospital provides access to a breast milk freezer or refrigerator, use it for milk storage and keep your pump kit in a clean bag in between sessions. When in doubt, follow whatever protocol your NICU team has outlined, since individual hospitals may have requirements that go beyond general guidelines.
How Long Parts Stay Sterile
There is no universal clock on how long sterilized parts remain “sterile” once removed from the sterilizer. In a practical sense, parts that have been fully dried and stored in a clean, closed space are safe to use for the next pumping session. If parts have been sitting in an open-air environment for several hours, or if anything has touched them (hands, countertops, other dishes), treat them as no longer sterile.
UV sterilizer cabinets with storage mode are the exception here, since they re-sterilize automatically on a set schedule. Outside of that technology, the safest approach is to sterilize close to when you plan to use the parts, or to store them properly and wash your hands before reassembling right before a session.
A Quick Storage Routine
Putting this all together, here’s what a good post-sterilization routine looks like. After your sterilizing cycle finishes, place parts on a clean, unused paper towel or dish towel in a spot away from dust and foot traffic. Let them air-dry completely. Once dry, wash your hands thoroughly, reassemble everything, and put the assembled parts into a closed cabinet, clean container, or UV sterilizer on storage mode. That’s it.
The whole process takes very little active effort. The waiting is the hard part, especially when you’re pumping every two to three hours and parts never seem to dry fast enough. Having two sets of pump parts can help enormously. One set dries and stores while the other is in use, so you’re never racing against the clock with damp flanges.