6 Sterilizing water for healthy term infants has historically been recommended until infants are four months of age. By four months infants are commonly putting many non-sterilized objects in their mouths. Therefore four months has been chosen as the age for discontinuing the sterilization of water.

In 2026, health organizations like the NHS and CDC generally recommend that you continue boiling water for baby formula until the infant is at least 6 to 12 months old. While most municipal tap water in developed countries is safe for adults, a baby's immune system is still developing and is more susceptible to bacteria like Cronobacter or Salmonella that can occasionally be present in water or even the powdered formula itself. Boiling the water and letting it cool to no less than 70°C (158°F) before adding the powder helps to sterilize the formula. Many pediatricians suggest that once a baby reaches 6 months and starts exploring the world (and putting everything in their mouth), the strict need for sterilized water decreases, but continuing until 12 months provides an extra layer of safety. Always consult your specific water quality report; if you use well water, you should continue boiling it or use tested bottled water until your pediatrician gives the all-clear.