Formula Dispenser

Study (2023): Formula Prep Machines Possibly Not Hot Enough, Posing GI Infection Risks

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formula prep machines possibly not hot enough


Formula-Fed Infants At Higher Risk Of GI Infections

A 2023 Maternal & Child Nutrition study explains that formula-fed babies are more likely to develop GI infections due to the following reasons: (1)

  • Possible presence of bacteria in their powdered infant formula (e.g., contaminated products that parents fed their children before these were subjected to a formula recall or due to unsanitary preparation such as not washing hands before handling the formula)
  • Potential bacterial contamination of their feeding equipment (e.g., baby bottles, formula dispensers, etc.), especially if not properly washed and sterilized
  • Improper formula preparation methods, including the use of water that isn’t hot enough to kill off possible pathogens in the formula


The WHO (World Health Organization) recommends that baby formula must be prepared using water with temperatures ≥70°C (≥158°F) to eliminate bacteria and reduce bacterial infection risks. (1)

What’s concerning is that the study discovered that formula prep machines are possibly producing water that’s not hot enough to kill off bacteria, posing GI infection risks. (more about this below) (1)


Formula preparation machines make it easier for parents to get their baby’s formula ready. They come in handy, especially during nighttime feeds.

However, the 2023 Maternal & Child Nutrition study found some worrying information: (1)

  • Only about 14.9% of formula prep machines in the study produced the recommended water temperature (≥70°C; ≥158°F).
  • The average water temperature from the automatic dispensers is 65.78°C (150.40°F; about 9°C or 48.2°F lower than kettles).
  • Many of the parents in the study didn’t understand the possible risks of bacterial contamination in powdered infant formula preparations.
  • Many of the parents didn’t follow the guidelines for preparing infant formulas.


Although the study was conducted in the UK, these might also apply to products sold and used in the US.

We didn’t find any studies on formula preparation machines conducted in the US. However, we’re sharing the results of this study to help you understand what can happen when formula prep machines don’t work as advertised.

This is especially concerning because the study also pointed out that formula-fed babies often experience GIs at higher rates than breastfed ones. (1)


2023 Study: Formula Prep Machines Not Producing Ideal Temperatures

In the 2023 Maternal & Child Nutrition study participated by 200 UK-based parents with infants younger than 12 months old, 143 were included in the temperature analysis of the water they use for formula preparation. (1)

These were the results of the study, based on the number of products (formula preparation machines vs. kettles) that produced a water temperature of ≥70°C (≥158°F):

  • Formula preparation machines: only 14.9% or 11 out of 74 
  • Kettle: 78.3% or 54 out of 69 


The mean or average water temperatures dispensed by these products were as follows:

  • Formula preparation machines: 65.78°C (150.40°F)
  • Kettle: 75.29°C (167.52°F)


Other Unsafe Practices In Formula Preparation

To further reduce contamination risks in infant formula preparation, aside from using adequately hot water, parents are also advised to: (1)

  • Wash their hands (before preparing the baby formula)
  • Regularly disinfect preparation surfaces
  • Wash and sterilize all feeding equipment


According to the study, the parents (in the UK) routinely washed and sterilized their baby’s bottles and teats (nipples). (1)

However, many failed to follow the other guidelines for safer formula preparation: (1)

  • 21.8% only washed their hands about half the time
  • 14.6% regularly prepared several bottles per batch instead of one at a time (for immediate use)


When asked, the parents explained that they weren’t always able to wash their hands due to the following reasons: (1)

  • They were in a rush 
  • They forgot to wash their hands
  • They were trying to comfort an upset baby
  • They were holding their baby, making it ‘impossible’ to wash their hands


Some parents explained that they didn’t wash their hands because they didn’t feel the need to do it due to the following reasons: (1)

  • They had recently washed their hands
  • They used a hand sanitizer instead of soap and water
  • They only touched parts of the baby bottle that their baby’s mouth won’t make contact with


Thankfully, about 69.5% of the parents said they cleaned and disinfected surfaces used for formula preparation ‘always’ or ‘most of the time’ before making their baby’s bottle. (1)

Yet it appears that unsafe formula preparation practices aren’t just limited to parents in the UK. 

The authors also referenced an older study in the US, published in the 2008 Pediatrics journal, showing unsafe formula preparation practices: (1)(4)

  • 55% didn’t always wash their hands with soap (before formula preparation)
  • 35% heated their formula bottles using a microwave oven
  • 32% didn’t adequately wash the bottle nipples between uses
  • 6% didn’t always discard baby formula left standing for over two hours


What You Can Do

Opt To Breastfeed Or Follow The Preparation Guidelines

Studies have shown that breastfeeding can protect your baby against infections, especially GI (gastrointestinal) acute infections, multiple respiratory illnesses, and acute otitis media (middle ear infection). (2)(3)

The AAP (American Academy of Pediatrics) estimates that breastfeeding can reduce the risks of GI infections by as much as 64% compared with formula feeding. (3)

However, not everyone can or wants to breastfeed. 

If you’re formula-feeding, we recommend following the guidelines for safe preparation detailed above.


Check Your Equipment: What Temperature Does A Perfect Prep Machine Do?

You can also check your formula prep machine if it produces the right water temperature ≥70°C (≥158°F) for 5-10 seconds during preparation to eliminate pathogens while still ensuring that the nutrients and bioactive factors (such as probiotics) aren’t affected. (3)


Regularly Check For Formula Recalls

It’s also important to regularly check baby formula recalls and other safety alerts to ensure that you can immediately stop giving your baby any potentially contaminated and harmful products.


Formula Recalls To Monitor



What Temperature Is The Hot Shot On The Prep Machine?

The ‘hot shot’ on formula prep machines can vary, but it’s supposed to be at least ≥70°C (≥158°F). 

You can check your machine’s settings and ensure you’re choosing the correct temperature (some settings might be below the ideal or required).


Why Is My Prep Machine Not Dispensing Hot Water?

Check your temperature settings. Some machines have options for lower settings (e.g., 104°F or 40°C). Change the settings to the ideal or maximum temperature.

If that doesn’t work, perhaps your machine is defective. Check your product manual for troubleshooting procedures, or contact the company to get your machine inspected and fixed.


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