Water for Formula: What to Use

If you are mixing infant formula at home, make sure you're doing so safely

Baby formula

Verywell / Bailey Mariner

All water essentially looks the same, but not all water sources are created equal. It's not just a matter of taste—it's also true in terms of drinking water safety, and it's especially true when it comes to what water to use for formula. You can use tap water if you are mixing infant formula at home, provided your tap water is safe for your baby. Or, you may need to use boiled or bottled water for formula. Also, baby water is available that is specifically designed to be safe for use in formula.

Tap Water Fluoride Levels

The American Dental Association (ADA) has issued concerns about water that contains higher concentrations of fluoride (greater than 0.7mg/l). Fluoride can be protective for dental health, but higher levels can cause fluorosis on developing teeth.

Fluorosis is not a tooth disease. Rather, it appears as discoloration on your baby's developing teeth, which may appear as white spots or streaks on the enamel. This imperfection of coloration develops on your baby's permanent teeth while they are still forming in the gums.

Most powdered infant formulas contain fluoride. The Centers for Disease Control and Prevention (CDC) recommends that if an infant is exclusively consuming infant formula reconstituted with fluoridated water, parents should use de-fluoridated bottled water part of the time. This will help reduce the risk of too much fluoride.

If you are using tap water, the ADA suggests checking with your local water company to make sure that the fluoride level in your water is less than 0.7 mg/L. This information is also available online via the CDC's My Water's Fluoride tool.

If you are mostly breastfeeding, and only using an occasional bottle that may have a slightly higher concentration of fluoride, ask your pediatrician if the limited exposure is acceptable.

Well Water Safety

If your home is supplied by well water rather than by a public water system, the American Academy of Pediatrics (AAP) recommends having your water tested for nitrates every 3 months for a year to make sure it is safe for your baby.

Nitrates naturally occur in plants and are used in fertilizers. They can also make their way into groundwater. When ingested regularly by infants (such as through formula) nitrates can lead to methemoglobinemia, a dangerous and potentially fatal condition that causes interference with the circulation of oxygen in the blood.

Boiling water will not reduce the nitrate concentration and could even increase it as the water evaporates. Mechanical filters also do not remove nitrates. That means that if the nitrate level in your well water is too high, you should use bottled water for formula preparation.

Choosing Bottled Water

If you are in a situation where you do not want to or cannot use tap water (whether at home or in public), the other option is to buy bottled water. You'll find some "nursery water" products that are marketed specifically for babies, but these are not necessary.

You can also choose low-fluoride bottled water that's labeled as purified, deionized, demineralized, distilled, or prepared by reverse osmosis. By law, any bottled water you purchase in the United States must meet the Food and Drug Administration (FDA)'s standards of water quality.

When to Boil Water

Product packaging used to state that all water used to make infant formula should be boiled. However, if you read the label on an infant formula today, you will most likely see a statement urging you to ask a healthcare provider whether or not you should boil the water before preparing formula for your baby.

The AAP instructs parents to use water from a safe source to mix infant formula. If you are concerned about your water source's safety, use bottled water or boil your water for 1 minute and allow it to cool for up to 30 minutes before using it to make the formula.

However, keep in mind that boiling water will only address bacterial contaminants, not chemicals. Powdered infant formula is not sterile and therefore it runs a risk of bacterial contamination.

The World Health Organization (WHO) guidelines for preparing formula state that all water (whether tap or bottled and purified) should be boiled before it is used, and mixed with the formula before the temperature drops below 70 degrees C (158 degrees F).

The WHO also states that if boiled water isn't available, a safe water source can be used to mix formula, but the reconstituted formula should be used immediately and not stored.

How to Use Water to Mix Formula

When preparing your baby's formula, follow the instructions on the formula labels. You also can check with other reliable sources like local WIC agencies and the Centers for Disease Control and Prevention. Here are some tips from the AAP for mixing your baby's formula with water.

  • Add water first, then powder. Always put the water in the bottle first, then add the powder, not the other way around.
  • Boil your water if needed. According to the AAP, infants under 3 months of age, those who were born prematurely, and those who have a weakened immune systems, should be given formula that is prepared with hot water in order to kill any microbes. Water should be boiled and cooled for 5 minutes before adding it to a clean bottle.
  • Test the formula temperature. To make sure the prepared formula is not too hot before feeding it to your baby, shake a few drops on your wrist. It should be cooled to body temperature before feeding. You can run a prepared bottle under cool water or place it in an ice bath if it is too hot.
  • Discard leftover formula. After feeding your baby prepared formula, discard what is left within 1 hour of the feeding. If you prepare the formula and do not feed your baby right away, you can store the formula in the refrigerator for up to 24 hours.

Never add water to premade (ready-to-feed) formula. Feeding your baby diluted formula is dangerous.

Ask Your Pediatrician

Discuss your plans for making formula with your pediatrician and find out what they recommend as the safest option. In addition to talking with your baby's doctor, the AAP also recommends checking with your local health department to find out if you can use unboiled tap water in your baby's bottle.

Remember that the WHO recommends boiling all water and using the hot water to reconstitute the formula to kill bacteria that could be lurking in the formula itself. Recommendations and water safety vary by location. This is why it's important to talk to your pediatrician about what is best for your family.

The AAP also stresses that parents should never water down infant formula—either to give their baby extra water or to make formula last longer and save money. Giving babies too much water can be dangerous and may lead to water intoxication.

Watered-down formula also delivers fewer nutrients in each feeding, which can slow growth and development and result in electrolyte imbalances that could cause seizures.

A Word From Verywell

Choosing the right water for your baby's formula should begin with a conversation with their healthcare provider. Because water sources and quality vary by region, your situation may be different than those in other communities. The key is to ensure that you are mixing your baby's formula with the best quality water available to you.

7 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hujoel PP, Zina LG, Moimaz SA, Cunha-cruz J. Infant formula and enamel fluorosis: a systematic review. J Am Dent Assoc. 2009;140(7):841-54. doi:10.14219/jada.archive.2009.0278

  2. Centers for Disease Control and Prevention. Infant formula.

  3. American Dental Association. Fluoride: Topical and systemic supplements.

  4. American Academy of Pediatrics. Where we stand: Testing of well water.

  5. U.S. Food and Drug Administration. Bottled water everywhere: Keeping it safe.

  6. American Academy of Pediatrics. How to safely prepare formula with water.

  7. World Health Organization (WHO). Safe preparation, storage and handling of powdered infant formula.

By Jennifer White
Jennifer White has authored parenting books and has worked in childcare and education fields for over 15 years.