PickedBaby
Guide

How to prepare baby formula safely: water, mixing and storage (2026)

Short answer: use safe water (most tap water is fine), measure exactly with the can’s scoop, add powder to water and shake in the bottle, and never add extra water. Use a bottle within 1 hour of starting a feed and toss leftovers; refrigerate unused prepared formula and use it within 24 hours. For babies under 3 months, preterm or immune-compromised, the CDC suggests ready-to-feed liquid or mixing powder with water hot enough to kill germs.

By PickedBaby Editorial TeamLast updated

Recalls checked November 10, 2026 on CPSC. We checked FDA outbreak and recall notices on November 10, 2026. Since November 2025, two infant formula brands were recalled in full for possible Clostridium botulinum contamination: ByHeart Whole Nutrition (all cans and “anywhere pack” sticks, recalled November 11, 2025; 48 infants hospitalized, no deaths; outbreak declared over February 26, 2026) and Nara Organics Whole Milk Powdered Infant Formula (all lots, recalled June 13, 2026; sold at Target and Nara.com). FDA says the two outbreaks share milk suppliers. Don’t use either product. Our recall-check policy.

How this page was made: this is a research-based guide built from official safety guidance (AAP/HealthyChildren.org, CPSC, NHTSA, FDA), federal safety standards and recall records, linked at the bottom of the page. We haven’t tested these products ourselves, and we don’t give scores. Our methodology.

Not medical advice. This page explains product safety guidance. For questions about your child’s health, feeding or development, ask your pediatrician.

Quick answer

Short answer: use safe water (most tap water is fine), measure exactly with the can’s scoop, add powder to water and shake in the bottle, and never add extra water. Use a bottle within 1 hour of starting a feed and toss leftovers; refrigerate unused prepared formula and use it within 24 hours.

Last updated Recalls checked 2026-11-10

Powdered formula isn’t sterile, so preparation and storage matter, especially for young or vulnerable babies. The AAP[1][2][6], CDC[3][4] and FDA[5][8] largely agree; where they differ in detail, we say so.

Step by step

  1. Wash hands 20 seconds; clean the prep area (CDC[3][4]).
  2. Use safe water: most municipal tap water is fine unless your area has a known contamination (AAP[1][2][6]). Unsure? Ask your local health department or use bottled water (FDA[5][8]).
  3. Put the water in the bottle first, then the powder (AAP).
  4. Measure exactly with the scoop that came with that can; level, unpacked scoops (AAP). Never add extra water (AAP; FDA).
  5. Cap and shake in the bottle. CDC says shaking or swirling in the bottle is safest; blenders have been linked to infant illnesses.
  6. Warming: one AAP page says a bottle made with room-temperature tap water just before feeding needs no warming; another AAP sheet says warming is best for babies under 6 months, using a bottle warmer, warm running water or a container of warm water for 5–10 minutes. Never use a microwave (CDC; AAP). Test drops on your wrist.

If you use tap water, the AAP suggests cold water from the faucet, since warm tap water may pull impurities from pipes.

How long does prepared formula last?

Prepared formula timing (AAP[1][2][6]; CDC[3][4]; checked November 10, 2026)
SituationUse within
Bottle your baby has started1 hour, then throw out the rest (AAP; CDC)
Prepared powder, not refrigerated2 hours of preparing (CDC)
Prepared formula, refrigerated right away24 hours (AAP; CDC)
Opened ready-to-feed or concentrate, covered in fridge48 hours (AAP)

Extra steps for newborns and higher-risk babies

For babies under 3 months, born preterm or with weakened immune systems, the AAP[1][2][6] and FDA[5][8] advise boiled water. The CDC[3][4] goes further for Cronobacter prevention: consider sterile ready-to-feed liquid; or boil water, let it cool no more than 5 minutes, mix the powder while the water is still very hot, then cool the capped bottle under cold water to body temperature and test it. (The AAP’s general guidance allows boiled water cooled longer; the CDC’s hot-mix method is the extra-cautious option.)

Who should skip this, and what to skip

If you use ready-to-feed liquid, skip the water steps entirely; never add water to it (AAP[1][2][6]).

  • Watering down formula: The AAP[1][2][6] says it can cause water intoxication and growth problems.
  • Giving water or juice under 6 months: The AAP[1][2][6] says babies don’t need it unless a pediatrician advises.
  • Microwaving bottles: CDC[3][4] and AAP[1][2][6] warn of hot spots that burn the mouth.
  • Blenders for mixing: CDC[3][4] says blenders have been linked to illnesses.
  • Saving a half-finished bottle for later: CDC[3][4] says baby’s saliva lets germs grow; throw it out.

Everything we tell parents to skip

The free or budget option

You need bottles, the can’s scoop and tap water. The AAP[1][2][6] says a bottle made with room-temperature tap water right before feeding needs no extra refrigerating or warming, so a warmer is optional. Make 2–4 ounce batches to waste less (AAP).

Frequently asked questions

Can I use tap water for formula?
Usually yes, unless your local water is known to be contaminated (AAP[1][2][6]). Use boiled water for very young or vulnerable babies (AAP; FDA[5][8]).
Do I need nursery water?
Our sources don’t require it; safe tap or bottled water works per the AAP[1][2][6] and FDA[5][8].
How long can formula sit out?
Use within 1 hour once feeding starts; prepared powder within 2 hours if not refrigerated (CDC[3][4]).
Should I clean the scoop?
CDC[3][4] says only if it gets dirty, then dry it completely before putting it back.

Sources

Safety guidance, standards and recall records come only from the official pages below, which we opened and read for this page. Retailer pages, if any, are used for price and specs only. This page lists no prices.

  1. AAP (HealthyChildren.org): How to Safely Prepare Baby Formula With Water, fetched Nov 10, 2026 (healthychildren.org)
  2. AAP (HealthyChildren.org): How do I mix and serve infant formula for my baby?, fetched Nov 10, 2026 (healthychildren.org)
  3. CDC: Preventing Cronobacter in Infants (formula preparation and storage), fetched Nov 10, 2026 (cdc.gov)
  4. CDC: How to Clean, Sanitize, and Store Infant Feeding Items, fetched Nov 10, 2026 (cdc.gov)
  5. FDA: Infant Formula: Safety Do's and Don'ts, fetched Nov 10, 2026 (fda.gov)
  6. AAP (HealthyChildren.org): How to Sterilize and Warm Baby Bottles Safely, fetched Nov 10, 2026 (healthychildren.org)
  7. AAP (HealthyChildren.org): How long can baby bottles sit out at room temperature?, fetched Nov 10, 2026 (healthychildren.org)
  8. FDA: Outbreak Investigation of Infant Botulism: Infant Formula (November 2025), fetched Nov 10, 2026 (fda.gov)
guide

How to choose an infant formula (2026)

Short answer: for most healthy full-term babies, a standard iron-fortified, cow’s-milk-based formula is the right start, and a store brand works as well as a name brand because all US formula must meet the same FDA nutrient rules. Choose a specialty formula (hydrolyzed, soy, preterm) only on your pediatrician’s advice. Before buying, check the brand isn’t recalled: ByHeart (2025) and Nara Organics (2026) were recalled for botulism risk.

guide

Do you need a bottle sterilizer? What the CDC and AAP say (2026)

Short answer: usually no. The CDC says to clean bottle parts after every feeding, and if your dishwasher uses hot water and a heated drying (or sanitize) cycle, no separate sanitizing step is needed. Sanitize at least daily if your baby is under 2 months, was born preterm or has a weakened immune system; boiling for 5 minutes works as well as a gadget. If you own a Baby Brezza SuperFast Sterilizer Dryer, check the November 5, 2026 recall.

guide

Do you need a bottle warmer or formula maker? (2026)

Short answer: neither is required. The AAP says a bottle made with room-temperature tap water right before feeding needs no warming, and a bottle can be warmed under warm running water or in a container of warm water. Never microwave a bottle (AAP; CDC). A formula maker is fine only if it measures exactly and you keep it scrupulously clean; it can’t change the 1-hour, 24-hour or extra-caution rules for young babies.

guide

Is homemade baby formula safe? Why the FDA and AAP say no (2026)

Short answer: no. The FDA advises parents not to make or feed homemade formula; it has received reports of babies hospitalized with low calcium (hypocalcemia) after homemade formula, and recipes risk contamination and missing nutrients. The AAP agrees. If cost or supply is the problem, ask your pediatrician, local health department, a food pantry or social services for help rather than mixing your own.

guide

Are plastic baby bottles safe? BPA, glass and choosing bottles (2026)

Short answer: yes. The FDA amended its rules in July 2012 so BPA-based polycarbonate is no longer provided for in baby bottles and sippy cups, because makers had abandoned it. The AAP’s precautions: avoid old clear bottles marked #7 or “PC”, don’t microwave plastic or heat it in the dishwasher if it’s polycarbonate, and consider glass if you can handle the breakage risk. The AAP says bottle type matters less than how you hold your baby.