How to Prepare a Safe Bottle of Formula, Every Time

Formula prep looks simple on paper: water, powder, mix, serve. In practice, new parents are often bombarded with conflicting advice — boil the water to exactly this temperature, never reheat, always sterilise for this long. Let's clear up the confusion with what's actually recommended in Australia, and how to make the process quicker without cutting corners on safety.

Understanding the Key Terms

Before diving into method, it helps to know the language:

Sterilised water

Water that's been brought to a rolling boil for at least one minute, either on the stove or in a kettle.

Cooled sterilised water

Previously boiled water that has cooled to drinking temperature or below. Water is generally considered sterilised for up to 24 hours after it first reaches boiling point.

Sterilising products

This refers to using boiling water, steam sterilisers, UV sterilisers, or cold-water chemical solutions to clean bottles, teats, and other feeding equipment.

Do I Need to Prepare Formula Above 70°C?

This is one of the most debated questions in formula feeding, so let's break it down properly.

The concern relates to a bacteria called Cronobacter sakazakii, which can occasionally contaminate powdered formula during manufacturing. The World Health Organization recommends preparing formula with water above 70°C specifically to destroy this bacteria. However, doing so also destroys some heat-sensitive vitamins and nutrients in the formula, and significantly increases the risk of burns from handling very hot water around a newborn.

For context, there have been zero reported cases of C. sakazakii infection in Australia over the past 40 years. Australia's Infant Nutrition Council instead recommends preparing formula at around 37°C — body temperature using water that has been sterilised (boiled) in advance and then cooled, provided the bottle is consumed within an hour of being made.

In short: preparing a bottle with lukewarm, previously sterilised water and feeding it to your baby within an hour is considered safe practice in Australia. Ultimately, safe bottle feeding comes down to a combination of factors — clean water, a well-maintained fridge, hygienic surfaces, and proper sterilising and storage of your equipment.

How to Make a Bottle of Formula, Step by Step

1. Wash your hands thoroughly, and make sure the bottle you're using has been properly cleaned and sterilised.

2. Read the instructions on your specific tin. Every brand differs slightly in its scoop-to-water ratio, so don't assume one tin's instructions apply to another.

3. Add the sterilised water to the bottle first, before adding any powder, so you can be sure of an accurate water measurement.

4. Add level scoops of formula, counting carefully. It sounds obvious, but losing count mid-scoop happens to almost everyone at some point.

5. Swirl, don't shake. Shaking can create air bubbles that lead to an unsettled tummy. Swirl gently until the powder is fully dissolved, then check the temperature is safe before serving.

6. Discard any unused formula. Never save a partially finished or made-up bottle for later — this encourages bacterial growth.

Skip the Manual Steps Altogether

If step three onward sounds like a lot to manage one-handed while holding a hungry baby, that's exactly the gap Beaba's Milkeo Plus was built to close. It automatically doses the correct amount of water and formula powder, mixes them evenly, and heats to your chosen temperature — room temperature, 37°C, or up to 70°C dispensing directly into the bottle in under 20 seconds. Its integrated mixing system also removes the lumps and hot spots that can happen with manual swirling, and a self-clean function keeps daily maintenance simple.

Sterilising Your Feeding Equipment

Sterilising bottles, teats, and other feeding parts before use is recommended for young babies. There are several common methods:

• Boiling water — free, but requires a full rolling boil for around 5 minutes.

• Steam sterilisers — automatic units that use steam, with sterilising time varying by model.

• UV sterilisers — automatic units using ultraviolet light to disinfect.

• Chemical sterilisation — antibacterial tablets or liquid dissolved in water, taking roughly 10–30 minutes.

Whichever method you use, always wash equipment thoroughly with dish soap or a bottle-specific detergent first, to remove any formula residue before sterilising.

For an all-in-one option at home, Beaba's BabyMilk 3-in-1 bottle warmer covers warming, sterilising, and reheating baby food in one compact unit — heating a bottle in around two minutes and sterilising a single bottle or set of bottle parts using steam. It's a straightforward option if you're after something simple that handles the basics without extra bells and whistles.

FAQ

Do I have to prepare formula with water above 70°C?
No. While the WHO recommends 70°C water to destroy potential bacteria, Australia's Infant Nutrition Council advises that preparing formula at around 37°C with previously sterilised, cooled water is safe, provided the bottle is used within an hour.

How long is boiled water considered sterile?
Water is generally considered sterilised for up to 24 hours after it reaches a rolling boil, provided it's stored appropriately.

Can I shake a bottle to mix the formula?
 It's better to swirl rather than shake, as shaking can introduce air bubbles that may upset your baby's tummy.

Can I save leftover formula for the next feed?
No. Any unused, made-up formula should be discarded rather than stored for a later feed, as this increases the risk of bacterial growth.

Do I need to sterilise bottles every time?
Yes, it's recommended to sterilise feeding equipment for young babies, using boiling water, a steam steriliser, a UV steriliser, or a chemical solution, after first washing off any formula residue.