Believe it or not, there is much confusion surrounding this topic. Many parents believe that cooled boiled water means water that has been brought to the boiling point and then refrigerated. In actual fact, cooled boiled water refers to boiled water that has been cooled for no more than 30 minutes (so it’s no cooler than 70 degrees) after boiling. It is the recommended method for making formula and needs to be consumed immediately after mixing to avoid bacteria growth.
According to the World Health Organisation (WHO):
For infants at greatest risk, sterile liquid infant formula should be used where available. If powdered infant formula is used, correct preparation and storage reduces the risk of illness. Powdered infant formula should be prepared with water that is no cooler than 70ºC (in order to kill E. sakazakii) and prepared feeds should be consumed immediately or stored in a refrigerator (to prevent growth of E. sakazakii).
Unlike commercial liquid formulas that are safe to consume, powdered infant formula cannot achieve commercial sterility. Bacteria has been found in infant formula and if not prepared fresh, can cause a life-threatening infection such as Cronobacter sakazakii and salmonella. Therefore, it is necessary to follow the guidelines endorsed by WHO, FAO and other medical organizations.
To effectively avoid the growth of bacteria, it is important to follow these steps.
- Fill the kettle or saucepan with fresh tap or nursery water. Bottled water is not sterile and can contain too much salt or sulphate for consumption by a baby.
- Boil the water. Do not use previously boiled water.
- Sterilize the bottle and all utensils in boiling water for 2 minutes. Ensure that the formula is mixed in a clean kitchen environment and that your hands are thoroughly washed.
- Add the cooled boiled water into the baby bottle. Water for babies under two months of age, or who have a low birth weight or a compromised immune system, must be cooled down to no less than 70 degrees. For all other infants, room or body temperature is adequate.
- Add the baby formula in accordance with the manufacturer’s instructions. Too little will not provide your baby with enough nourishment.
- Screw on the bottle lid and shake until dissolved.
- Cool the bottle under cold running water or in a container of cold water; make sure the water is below the nipple level if you choose the latter method.
- Test the temperature.
- Feed the baby. If a feed takes longer than one hour, it is best to finish the feed with a new batch of formula.
- Discard any unused formula.
The formula that is prepared for later use in this manner and stored in the refrigerator, must be consumed within 24 hours. Formula should only be removed from the fridge just prior to use. Reducing the amount of time from preparation of the formula to feeding the baby will lessen the risk of bacteria. It is best that microwave ovens are not used to warm formula in the event of uneven heating that can burn a baby’s mouth.
If you are travelling, it is preferred that you take one or more sterilized bottle of cooled boiled water so that the formula can be added as you need it. Alternatively, you can opt for a ready to feed liquid formula for ease. If you are not able to do this, we suggest you follow these guidelines:
- If the formula is kept in a fridge, use within 24 hours.
- If it is kept alongside an ice pack, consume within 4 hours.
- If the formula is kept at room temperature, use within one hour.
As a baby’s immune system is not as well developed as that of an adult, it is imperative you take the necessary precautions. Pre-term babies and those with a low birth weight are particularly at risk.
Susannah is a certified Birth Doula through Childbirth International and the founder of Trimester Talk. With a background in journalism and digital strategy, she combines evidence-based research with real-world knowledge to create accessible content about pregnancy and parenting. She’s a mother of two and stepmother of two more, all of them now teenagers.