Breast pump parts should be sterilized (or sanitized) once a day, in addition to washing them after every use. The CDC recommends this daily sanitizing step as a deeper clean that eliminates bacteria your regular soap-and-water wash might miss. For brand-new pump parts or secondhand equipment, sterilize before the very first use as well.
Daily Sanitizing vs. Washing After Each Use
These are two different steps, and both matter. After every pumping session, all parts that touch breast milk need to be taken apart and washed with soap and warm water. This removes milk residue, which is a breeding ground for bacteria. A brush dedicated only to pump parts helps reach inside flanges and connectors.
Once a day, on top of that regular wash, you sanitize. This is the step that kills the more stubborn organisms that soap alone can leave behind. You don’t need to sanitize after every single session, but skipping it entirely raises the risk of bacterial buildup over time.
Why Daily Sanitizing Matters
Pump parts that sit damp or aren’t properly sanitized can harbor dangerous bacteria. A CDC investigation linked two infant infections to a bacterium called Cronobacter sakazakii, which was recovered from breast pump parts cleaned in a household sink. This organism causes meningitis and bloodstream infections in young infants, with a fatality rate approaching 40% in infants who develop meningitis. Survivors often face permanent neurological damage.
In one of the investigated cases, pump parts had been cleaned and sanitized but were sometimes assembled while still moist. That detail matters: bacteria thrive in moisture. After sanitizing, let every part air-dry completely on a clean towel or drying rack before reassembling or storing.
How to Sanitize Pump Parts
There are three common methods, and all are effective when done correctly.
- Boiling water: Place disassembled parts in a pot of boiling water for five minutes. Use tongs to remove them and set them on a clean surface to air-dry.
- Microwave steam bags or sterilizers: These use steam generated inside a sealed container. Follow the manufacturer’s timing instructions, which typically run two to six minutes depending on the product and microwave wattage.
- Dishwasher with a sanitize cycle: If your dishwasher has a heated drying cycle and a sanitize setting, this counts as a valid daily sanitizing method. Put small parts like valves and membranes in a closed-top basket or mesh laundry bag so they don’t fall through the rack. Check your pump manufacturer’s guidelines first, since not all parts are dishwasher-safe.
Whichever method you choose, always start with parts that have already been washed with soap and water. Sanitizing isn’t a substitute for washing. It’s the second step.
How Sterilizing Affects Part Lifespan
Frequent sterilizing takes a toll on the flexible silicone and rubber components of your pump. Valves and membranes are the parts most affected, and knowing when to replace them keeps your pump working efficiently. A worn valve or membrane reduces suction, which means less milk output per session.
For duck valves (the one-piece silicone valves), expect to replace them every two to three months if you pump once a day or less. If you pump frequently throughout the day, replacement drops to every three to four weeks. Membrane flaps follow a similar pattern: roughly every six weeks for occasional pumping, and every two to four weeks for frequent pumping.
To get the most life out of these parts, avoid steam sterilizing in the microwave more than necessary, and skip the dishwasher for valves and membranes. The intense heat from both methods breaks down the elasticity of silicone faster than hand-washing with warm water. If you’re pumping multiple times daily, having a spare set of valves on hand prevents a surprise drop in suction from catching you off guard.
When You Can Ease Up
The daily sanitizing recommendation is most important for infants under three months, babies born prematurely, and infants with weakened immune systems. These groups face the highest risk from bacterial contamination. For older, healthy babies, some parents scale back to sanitizing every few days rather than daily. The regular soap-and-water wash after each session remains non-negotiable regardless of your baby’s age.
If you’re using the refrigerator storage hack, where you place unwashed pump parts in a sealed bag in the fridge between sessions and wash them all at the end of the day, know that the CDC does not recommend this method. Cold temperatures slow bacterial growth but don’t stop it. Each session adds a new layer of milk residue, and the cumulative bacterial load can become significant over a full day.
Quick Reference for Pump Part Care
- After every session: Disassemble, wash with soap and warm water, rinse, air-dry on a clean surface.
- Once daily: Sanitize using boiling water, steam, or a dishwasher sanitize cycle.
- Before first use: Sanitize all new or secondhand parts.
- Valves and membranes: Replace every 2 to 6 weeks depending on pumping frequency.
- After sanitizing: Let parts dry completely before reassembling or storing.