Infant Formula Safety: Water Temperature, Storage and Recalls

The short answer: powdered infant formula is not sterile¹. Most of the time, following the instructions on the container is enough. For babies under 2 months, born prematurely or with a weakened immune system, mix it with water that has been boiled and cooled slightly, to around 70°C¹. Start a made-up feed within 2 hours, and throw away whatever is left¹.

Why is formula safety in the news?

The FDA has put the industry on notice. On 13 July 2026, the US Food and Drug Administration (FDA) wrote to infant formula manufacturers and their suppliers calling for tighter oversight of ingredients and finished products². The letter pointed to two kinds of event:

• Two multistate outbreaks of infant botulism linked to powdered formula from two brands, ByHeart and Nara Organics, both of which issued voluntary recalls
• A cereulide contamination event from late 2025 into early 2026, with nearly 150 suspected and confirmed cases across 10 countries, traced to arachidonic acid (ARA) oil used in infant formula

The 2026 outbreak is over. According to the FDA, 4 infants became ill, all were hospitalised and none died, across 3 US states. The company recalled all lots on 13 June, and the US CDC declared the outbreak over on 27 August. The FDA states that the product was not distributed outside the United States, and that its investigation into the root cause is continuing³.

There is good news too. On 29 April 2026, the FDA published results from its largest-ever testing of infant formula: more than 300 samples and more than 120,000 data points, covering lead, mercury, cadmium, arsenic, pesticides, PFAS and phthalates. An overwhelming majority of samples had undetectable or very low levels⁴.

Taken together: the overall supply is safe, and individual lots are recalled when something goes wrong. The part you control is how formula is prepared and stored at home.

Why is powdered formula "not sterile"?

The CDC states that powdered infant formula is not sterile and can sometimes contain germs such as Cronobacter¹. The NHS likewise notes that even sealed tins and packets of powdered formula can sometimes contain bacteria⁵. These infections are rare, but they can be serious in young infants¹.

How hot should the water be?

Official advice is not identical everywhere:

Agency	Who it applies to	What to do
US CDC1	Most babies, where tap water is safe	Follow the manufacturer's instructions
US CDC1	Babies under 2 months, born before 37 weeks, or with a weakened immune system	Boil the water and wait about 5 minutes before mixing (around 70°C is needed to kill germs), then cool the feed before giving it
UK NHS5	All babies	Boil the water and leave it to cool for no more than 30 minutes, so it stays at 70°C or above when mixed

Follow your local health authority and the instructions on the container. If in doubt, take the more cautious option.

If you use a formula preparation machine, the NHS advises checking that the water is at least 70°C when it mixes with the powder⁵.

What are the key steps when making up a feed?

1. Wash your hands, and clean and disinfect the work surface. Bottles and teats need to be washed and sterilised¹⁵
2. Water first, powder second, using exactly the amount of water in the instructions¹
3. Use only the scoop that comes with the formula, and level it off⁵
4. Add neither extra powder nor extra water. Too much water means the feed may not meet your baby's nutritional needs. Too little makes the kidneys and digestive system work too hard and can cause dehydration¹
5. Cool the bottle under cold running water, then test a few drops on the inside of your wrist. It should feel warm, not hot¹⁵
6. Never warm formula in a microwave. It heats unevenly and can burn your baby's mouth¹⁵

For how much to offer each day, see our milk intake guide.

How long do made-up feeds and opened tins keep?

• A made-up feed: start it within 2 hours of preparation, and finish it within 1 hour of the start of feeding¹
• Not using it within 2 hours: refrigerate it immediately and use it within 24 hours¹
• Leftovers: throw them away, never save them for the next feed¹⁵
• An opened container of powder: keep the lid tightly closed, in a cool, dry place, not in the fridge. Most need using within 1 month of opening, so write the date on the lid¹
• Never use formula after its use-by date¹

The NHS is more cautious: it is best to make up feeds one at a time, as your baby needs them⁵.

What should you do if your formula is recalled?

The FDA's advice to parents in this outbreak is a practical template³:

• Stop using the recalled product and throw it away
• Wash bottles, counters, formula dispensers and anything else that touched the formula in hot soapy water or a dishwasher
• Get medical care immediately if your baby develops the symptoms below

When checking a recall, rely only on notices from the regulator in your own country, and compare the brand, product name and lot number line by line.

What are the signs of infant botulism?

The FDA describes it this way: most affected infants first develop constipation, poor feeding, loss of head control and difficulty swallowing, which can progress to difficulty breathing. Symptoms can take several weeks to appear after the formula was consumed³. The CDC's list for infants also includes drooping eyelids, a face showing less expression than usual, and a weak cry that sounds different from usual⁶.

Botulism is a medical emergency. If you see these signs, get medical care immediately. Do not wait⁶.

The CDC also notes that most infant botulism cannot be prevented, with one clear exception: do not feed honey to a child younger than 1 year old⁷.

Common questions

Can I use bottled water to make up formula? It depends on local guidance. The NHS does not usually recommend it, because bottled water is not sterile and may contain too much sodium or sulphate, and reserves it for when tap water is unavailable or contaminated⁵. The CDC advises bottled water in an emergency when tap water is not safe¹.

My baby's formula isn't one of the recalled brands. Should I switch? Not because of the headlines. The FDA's large-scale testing concluded that the US infant formula supply is safe overall⁴. If you have a specific concern, ask your paediatrician.

Will an extra scoop keep my baby full for longer? No. Formula that is too concentrated can make your baby constipated or dehydrated⁵, and it puts extra strain on the kidneys¹.

I'm breastfeeding. Do I need to know this? You will if you combination feed or move to formula later. For the basics of breastfeeding see Breastfeeding basics, and check other feeding claims in our myth-busting library.

This article summarises public information from the US FDA, the US CDC and the UK NHS, and covers general principles only. Advice on water temperature and storage times differs slightly between countries, so follow your local health authority and the product instructions. If your baby has any of the symptoms described, get medical care immediately.

References

Footnotes

1. Centers for Disease Control and Prevention. (2026, May 14). Infant formula preparation and storage. https://www.cdc.gov/infant-toddler-nutrition/formula-feeding/preparation-and-storage.html ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹

2. U.S. Food and Drug Administration. (2026, July 13). FDA calls on infant formula industry to better safeguard against contaminants introduced through their supply chain. https://www.fda.gov/food/hfp-constituent-updates/fda-calls-infant-formula-industry-better-safeguard-against-contaminants-introduced-through-their ↩

3. U.S. Food and Drug Administration. (2026, August 27). Outbreak investigation of infant botulism: Powdered infant formula (June 2026). https://www.fda.gov/food/outbreaks-foodborne-illness/outbreak-investigation-infant-botulism-powdered-infant-formula-june-2026 ↩ ↩² ↩³

4. U.S. Food and Drug Administration. (2026, April 29). FDA releases results from largest-ever testing of infant formula in the U.S. https://www.fda.gov/news-events/press-announcements/fda-releases-results-largest-ever-testing-infant-formula-us ↩ ↩²

5. NHS. (2023, August 31). How to make up baby formula. https://www.nhs.uk/baby/breastfeeding-and-bottle-feeding/bottle-feeding/making-up-baby-formula/ ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹

6. Centers for Disease Control and Prevention. (2024, April 1). Symptoms of botulism. https://www.cdc.gov/botulism/signs-symptoms/index.html ↩ ↩²

7. Centers for Disease Control and Prevention. (2026, February 26). Botulism prevention. https://www.cdc.gov/botulism/prevention/index.html ↩