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Is it OK to use warm tap water in baby’s formula?
Q: I have a 3-month-old baby that I’ve just adopted. I’m feeding her formula, which I mix up from the powder. She prefers her bottles warmed. Is it OK to use hot water from the tap to make her bottles? And, what’s the best way to warm my baby’s bottles?
Sharon Inglewood
A: Sharon, congratulations on your new baby! Babies can drink cool formula, but many seem to prefer warm milk, as it would be straight from the breast.

Although it might seem convenient to make up formula from warm tap water, this is not safe according to the U.S. Environmental Protection Agency (EPA). Compared with cold tap water, warm water is far more likely to carry lead that has leached out from the plumbing. Lead levels in drinking water tend to be highest in homes built before 1930 with lead pipes; homes less than 5 years old with copper pipes and lead solder, and homes with brass faucets or fittings.

Elevated lead levels are also more likely if your water is naturally soft, which tends to corrode the pipes more. The longer water stands in the pipes, the more lead is likely to become dissolved in it. Lead can be especially toxic for fetuses, infants and young children, causing delays in physical and mental development, kidney problems and anemia.

If you use tap water to make up your baby’s formula, it’s best to use cold water after you’ve let it run for one to two minutes to flush out the standing water that may contain more lead. To warm up the bottle, either run it under hot tap water or heat it in a pot of water on the stove or in a Crock-Pot. After heating the bottle, be sure to shake it well and test the temperature on the inside of your wrist to make sure it’s not too hot for your baby to drink. Although it may be faster to heat the bottle in the microwave, this is not recommended since it heats liquids unevenly and you can get scalding hot pockets in the milk, which can seriously burn babies’ mouths.

You may consider getting your tap water tested for lead. Contact your local water utility or public health department for information about testing. The authorities may test your tap water for you, or refer you to a qualified laboratory.

Instead of using tap water, you may consider using bottled water or filtered water for baby formula and food, cooking and drinking. Check that the bottled water has been tested for lead and that the filtration system has been certified to reduce or eliminate lead. Visit NSF International, a non-profit agency that tests and certifies bottled water and water filters, at www.nsfconsumer.org/bottled_water.asp, or call 1-877-867-3435. Or, visit the EPA website www.epa.gov/safewater/hotline/index.html or call the EPA Safe Drinking Water Hotline at 1-800-426-4791.

Because most bottled water and filtered water does not contain fluoride, a fluoride supplement may be necessary. Ask your baby’s doctor about this.

Karen Sokal-Gutierrez M.D., M.P.H. Pediatrician