Water used for mixing infant formula must be from a safe water source, as defined by your state or local health department.
If you are concerned or uncertain about the safety of the tap water:
You may use bottled water or bring cold tap water to a rolling boil for 1 minute (no longer), then cool the water to room temperature for no more than 30 minutes before it is used.
Important Message for Parents:
Watering Down Formula is Dangerous!
News reports have found parents diluting formula to try and save money or feeding water in addition to breast milk or formula. This can lead to a dangerous condition called water intoxication. The American Academy of Pediatrics (AAP) wants to remind parents to avoid these practices.
Babies do not need water in addition to formula. Adding extra water to formula reduces the about of nutrients baby will receive at each feeding. This can slow growth and development. Extra water also disturbs electrolyte balances which can lead to seizures. So always mix formula as directed by the manufacturer. If you're using formula but having trouble affording it check with your pediatrician, local health department, food pantry or social service agency.
How to test the temperature of a bottle:
Warmed water should be tested in advance to make sure it is not too hot for an infant. The easiest way to test the temperature is to shake a few drops on the inside of your wrist. Otherwise, a bottle can be prepared by adding powdered formula and room temperature water from the tap just before feeding. Bottles made in this way from powdered formula can be ready for feeding, as no additional refrigeration or warming would be required.
How long is the bottle of formula good for after making it?
Prepared formula must be discarded within 1 hour after serving an infant.
Prepared formula that has not been given to an infant may be stored in the refrigerator for 24 hours to prevent bacterial contamination.
An open container of ready-to-feed formula, concentrated formula, or formula prepared from concentrated formula, should be covered, refrigerated, and discarded after 48 hours if not used.