Skip to content
Life Guide U.S. essentials
English

Mix formula with water above 70 ℃, let it cool before feeding, and throw away what is left

  • High value
  • Evidence A
  • Buys life
  • Disputed
  • For: Child under 3, Pregnant or trying
  • Free
  • Takes minutes
  • Some willpower

In plain words

Formula is not sterile, and it may carry a kind of bacterium. If a newborn is infected, between 40% and 80% die. When you mix, first pour hot water into the bottle, wait until it cools to about 73.8 ℃, and then add the powder. That kills this germ down to less than one hundred-thousandth (十万分之一) of the original. Hot water leaves a little less vitamin C, but the formulas that were tested still met the standard. Let it cool after mixing before you feed, and throw away what is left.

Cost

Free. You wait a few extra minutes for the milk to cool each time. The hard part is waiting for the water to cool down when the baby is crying with hunger.

What you get

Formula is not sterile and may carry Cronobacter sakazakii (阪崎克罗诺杆菌). The reported death rate of newborns after infection is 40% to 80%. Laboratory studies show that if you pour hot water into the bottle first, wait until it cools to about 73.8 ℃ and then add the powder, in most cases the milk is still above 70 ℃. That reduces this germ by more than 5 log, to less than one hundred-thousandth (十万分之一) of the original. The cost of hot water: the data seen by a 2006 expert meeting of the WHO and the UN Food and Agriculture Organization (FAO) showed that with boiling water only vitamin C was clearly reduced, by 5.6% to 65.6% across 4 formulas. Formula already has extra vitamin C added at the factory; even the one that lost the most still had 9.0 mg per 100 kcal after mixing, above the lower limit of 8 mg in the international Codex Alimentarius food standard. The meeting saw only this one study, so it drew no conclusion from it.

Notes

A dispute: in a 2022 opinion, Germany's Federal Institute for Risk Assessment (德国联邦风险评估研究所) said that for healthy full-term babies, water at 20 to 50 ℃ is enough. It notes that most manufacturers' cans also say 40 to 50 ℃. Its reasoning is that 70 ℃ water poured into a bottle cools very quickly, so the germs actually killed are fewer than calculated. Hot water also destroys some nutrients, and feeding before the milk has cooled can scald the baby. In 2004 the European Society for Paediatric Gastroenterology, Hepatology and Nutrition also did not favor mixing with boiling water, worried about destroying vitamins and the probiotics added to the formula. The WHO and FAO still recommend above 70 ℃. Premature babies, babies with a birth weight under 2500 grams, babies under 2 months and babies with weak immunity are at highest risk; mix for them at 70 ℃, or ask a doctor. For healthy full-term babies, mix at the temperature on the can; this German opinion considers the infection risk extremely low. The 70 ℃ threshold comes from public health guidance. In the words of Beary and colleagues: “public health guidelines for caregivers of high-risk infants recommend reconstituting powdered infant formula with water heated to at least 70 ℃ (158 ℉) to inactivate microorganisms.” Don't use water that has sat in a thermos for a day. And don't leave mixed milk at room temperature to feed at the next meal.

Evidence grade
A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.
Sources
  1. Beary MA, Daly SE, Baker J, Snyder AB (2025). Assessing Hot Water Reconstitution Instructions and Labeling of Powdered Infant Formula to Ensure Cronobacter spp. Reduction. Journal of Food Protection, 88(9), 100571. https://doi.org/10.1016/j.jfp.2025.100571
  2. Sima WG, Legesse T, Girma S, et al. (2025). Emerging microbial risks: Cronobacter sakazakii in powdered infant formula for infants under six months of age in Ethiopia. BMC Microbiology, 26, 307. https://doi.org/10.1186/s12866-025-04380-y
  3. World Health Organization & FAO (2007). Safe preparation, storage and handling of powdered infant formula: guidelines. https://www.who.int/publications/i/item/9789241595414
  4. Bundesinstitut für Risikobewertung (2022). Recommendations for the hygienic preparation of powdered infant formula. Updated BfR Opinion No. 009/2022. https://doi.org/10.17590/20220510-104706
  5. Agostoni C, Axelsson I, Goulet O, et al. (2004). Preparation and handling of powdered infant formula: a commentary by the ESPGHAN Committee on Nutrition. Journal of Pediatric Gastroenterology and Nutrition, 39(4), 320-322. https://doi.org/10.1097/00005176-200410000-00002
  6. Silano M, Paganin P, Davanzo R (2016). Time for the 70 °C water precautionary option in the home dilution of powdered infant formula. Italian Journal of Pediatrics, 42, 17. https://doi.org/10.1186/s13052-016-0228-9
  7. Losio MN, Pavoni E, Finazzi G, et al. (2018). Preparation of Powdered Infant Formula: Could Product's Safety Be Improved? Journal of Pediatric Gastroenterology and Nutrition, 67(4), 543-546. https://doi.org/10.1097/MPG.0000000000002100

Translated from the Chinese original. Original book, section 20, tip 5. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer