Debating between breast-feeding and formula-feeding? EWG recommends breast-feeding if possible for at least the first 12 months of your baby’s life.

However, there are valid reasons a family might need to use formula. One in every four American newborns consumes formula from birth. Around two-thirds of these babies drink some formula by the time they are three months old.

The good news is, the Food and Drug Administration enforces safety and quality standards during infant formula manufacturing, such as requiring testing for disease-causing bacteria. Formula recalls are very rare. But unhealthy contaminants could be sneaking into your baby’s formula through an unlikely source: drinking water.

Parents can purchase formula in ready-to-feed, liquid concentrate and powder forms. Since both liquid concentrate and powder formula have to be mixed with water, using safe water is essential for babies’ health.

The FDA and American Academy of Pediatrics agree that it’s safe in most cases to use tap water that has been boiled for one minute and cooled to room temperature. This may be necessary for newborns and medically vulnerable babies. While boiling is sufficient to kill germs in the water, it won’t remove contaminants than can affect your baby’s health.

Lead, perchlorate, the herbicide atrazine and the nonstick chemical PFOA are among the harmful chemicals that have contaminated some major municipal water supplies in recent years.

Fluoride is another concern. About two-thirds of American households drink fluoridated tap water. Although municipal water utilities have added fluoride to public sources for decades, some health experts worry about the amount of fluoride formula-fed babies consume. EWG recommends that parents take steps to limit fluoride ingestion for formula-fed babies. 

Before mixing your baby’s next bottle, learn about the quality of your tap water. Public drinking water utilities regularly test their water and are required to disclose the results. Visit EWG’s Tap Water Database for an in-depth analysis of water quality, available for nearly 50,000 water companies or utilities nationwide.

Once you know if your water may have harmful contaminants, you may want to invest in a quality water filter. Some filters are more effective than others at removing specific contaminants. A basic carbon filter will reduce chlorine and lead in your water, but may not remove other contaminants. Visit EWG’s Water Filter Buying Guide to find the best filter for your needs.

On the go, use bottled or distilled water. And once you’ve prepared your baby’s bottle, throw away any formula they have not finished within one hour of serving. Store prepared formula for up to 24 hours, then discard. Never warm a bottle in the microwave or add more water to formula than the label instructs. Check the temperature of formula before serving by releasing a drop onto your wrist.