How to prep formula

Mom preparing formula

Unless your doctor tells you otherwise, you should add only water to formula in the amounts directed on the package. Following the preparation instructions is important to ensure your baby receives proper nutrients. Too much water will dilute the formula and too little water will concentrate it, and either can undermine the nutrition your baby might otherwise receive.

Practicing proper hygiene is also key when preparing formula. Your baby’s immune system is still developing so minimizing unnecessary exposure to bacteria can help decrease the risk of infections.

Now wash your hands and get ready to prepare your baby’s first bottle!

What to Do

Check expiration dates

Note the expiration dates on the formula packaging before serving. Make sure the cans or containers do not have dents.

Work in a clean area with clean bottles and other equipment

Wash your hands and work on a clean counter before handling baby bottles and formula. If you’re using the bottles for the first time, sterilizing the bottles along with their parts is a good precautionary measure. Simply boil the items for 5 minutes and then let cool before handling.

Otherwise, clean the bottles, bottle liners and nipples in hot soapy water and rinse well. You can use a special bottlebrush to clean any hard to reach spots.

Heating Water

It’s important to note that powdered infant formula is not sterile; it may harbor a rare but dangerous bacteria called cronobacter. Because of this, some organizations like the World Health Organization (WHO) recommend against powdered formula use in infants less than 1 month old. Sterile liquid (concentrate or ready-to-feed) is a safer option should you be concerned.

Here are instructions on how to safely prepare powdered formula:

  • Boil safe water (this can be bottled water or tap water if contaminant levels are low). Let the water come to a rolling boil.
  • Carefully pour the water into the feeding container you will be using to feed baby.
  • Let the water cool to no more than 158 degrees F (70 degrees C). In other words, let the water cool in the feeding container for about 10 minutes. Do not let it cool for more than 30 minutes. Cooling the water prevents the formula from clumping and destroying heat-labile nutrients like Vitamin C.
  • For more info, see the WHO’s formula prep brochure or the CDC’s instructions

*Note: According to the CDC, boiling the water decreases the risk of infection from bacteria that could be present in the formula itself. However, the American Academy of Pediatrics only recommends boiling water for formula when the quality of the water being used is in question. Discuss the above recommendations with your baby’s pediatrician.

Water Type

If your city or town has safe drinking water with low levels of contaminants such as lead, then it is usually fine to use cold drinking water to boil for formula use. Formulas contain a low amount of fluoride, but some municipal or well water can be high in fluoride which could cause mild dental fluorosis. Distilled water, purified water, or de-ionized water are typically lower in fluoride and may be less likely to cause Fluorosis. Speak with your pediatrician should you have a concern. For more information click here.

Mix infant formula with water according to package instructions

Check and follow the water-to-formula ratio on the package instructions as not all formulas use the same concentrations.

Formula instructions usually indicate to pour the water first and then add the powdered or concentrated liquid formula. Check the manufacturer’s recommendations.

Use a measuring cup for the water and the provided scoop for powder formula.

Close containers of infant formula or bottled water as soon as possible.

  • Immediately after mixing the formula with water, cool the formula by running the bottle under cold tap water or placing in a bowl of ice or cold water.
  • Test the temperature of the formula by dropping on the inside of your wrist.

Store prepared formula safely

  • One day’s worth of bottles can be prepped and stored immediately in the fridge in advance.
  • Prepared formula can be stored in the refrigerator for up to 24 hours before using. Do not freeze prepared formula.
  • Prepared formula should not be without refrigeration for more than 2 hours.
  • Once baby begins to drink formula, it must be used within 1 hour. Any remaining after the hour must be thrown out.
  • Powdered formula can be used for one month after it has been opened. We don’t recommend using the formula after the 30 days of opening because the nutrients start to degrade. Also, if any water or moisture comes into contact with the formula, bacteria may begin to grow.
  • Open ready-to-feed or concentrate formula (prepared or unprepared) can be refrigerated for 48 hours.

If you can’t remember how long you have kept formula in the refrigerator, it is safer to throw it out than to feed it to your baby.

As always, if you have any questions, feel free to chat live with our infant nutrition experts!

For more information, see the WHO’s formula prep brochure or the CDC’s instructions.