Fat emulsifiers are added to the ready to feed and concentrate forms to keep fat in suspension during storage. Also, forms that require added water will differ in content from ready to feed because of the minerals in the water. These differences are usually inconsequential to the baby. Only rarely will a baby have any type of intolerance to a different form of the same formula. You need not sterilize the water or bottles unless you have your own well.
Most bottled waters contain no fluoride.
Fluoride supplementation is recommended for infants after six months of age. A parent may choose to use a fluoridated water source to mix concentrate or powdered formula or obtain a prescription for fluoride drops from us. An infant does not usually need extra water between feedings. However, your pediatrician may recommend water if your infant has firm bowel movements or the weather is particularly warm. Once formula is mixed it should be refrigerated until used.