For many parents who are new to using infant formula, it's common to have questions about the best water to mix with powdered or concentrated liquid formula. While you may not need to spring for the expensive nursery water from the baby isle, the best choice of water will depends on your water source and how often you feed your baby formula.
Safe Tap Water
Tap water can be suitable for mixing with infant formula. However, before you use your tap water, consult with your local health department about the safety of the water, advises the American Academy of Pediatrics. If you find that your tap water is suitable, use room temperature tap water to prepare the infant formula.
Questionable Tap Water
Tap water can contain various contaminants, such as bacteria, parasites, minerals and chemicals. Always use water from the cold tap for food preparation and making baby formula, and run the water for one minute before you use it. If you have any doubt about the safety of your tap water, the AAP recommends boiling it for one minute and then cooling it to room temperature for precisely 30 minutes before mixing the formula. Do not cool the water for more than 30 minutes, because bacterial contamination could result.
If you feed your baby only formula and your tap water has fluoride in it, it’s possible that your baby could develop fluorosis -- light markings on the teeth -- warns the Centers for Disease Control and Prevention. To avoid this issue, use bottled water with low or no fluoride at least part of the time when you prepare your baby’s formula. Labels on this water will state “deionized,” “demineralized,” “distilled” or “purified,” according to the CDC.