How to prepare a bottle feed

To help protect babies from infection, knowing how to make up feeds and sterilise equipment correctly is essential

It is important to remember that powdered infant formula milk is not a sterile product. Correct preparation and handling is therefore vital to reduce the risk of serious illness in babies. Each feed should be made up as it is required. Storing pre-made infant formula milk may increase the chance of a baby becoming ill and should be avoided.

Clear instructions can be found on infant formula milks, so take time to familiarise yourself with the steps. Key points include:

  • All equipment (e.g. bottles, teats, caps, tongs) should be sterilised, surfaces cleaned and hands washed
  • Freshly run tap water should be boiled in a kettle and allowed to cool to no less than 70ºC to kill any bacteria present in the powdered formula, which means leaving the water for no more than 30 minutes, on average, after boiling. It is important that the water is still hot, otherwise any bacteria present in the milk powder may not be destroyed.

N.B. The required temperature for some specialist milks will vary – always check the pack first. 

  • The instructions on the pack should be read by parents to find out the amount of water that is needed per feed; the correct amount of water should be poured into a bottle
  • The scoop provided with the infant formula milk should be used to add the powder to the water, levelling off each scoop with a leveller (provided in the pack) or with the straight edge of a clean, dry knife. The powder should not be ‘packed down’ into the scoop
  • The teat should be placed back onto the bottle, covered and shaken gently to dissolve the powder. The bottle can be held under cold water until it is lukewarm before offering to the baby. Shaking a few drops onto the inside of the wrist will test the temperature
  • Any remaining milk should be thrown away when the baby has finished feeding and within two hours of being made up.

N.B. Ordinary tap water is best. Artificially softened, filtered and repeatedly boiled water should not be used to make feeds, as mineral levels may be too high. When using still, bottled water, the sodium level needs to be less than 200mg per litre and the fluoride level less than 1.5mg per litre. Water or formula powder should not be added to make a feed stronger or weaker unless advised to do so by a healthcare professional. Food should never be added to a baby’s bottle.

Bottle feeding checklist

Parents will need the following equipment, whether they are bottle feeding with infant formula or expressed breast milk:

  • At least three to four bottles with teats and caps
  • A bottle and teat brush
  • Sterilising equipment
  • Teat tongs.


Babies are most vulnerable to infections during their first year of life and as milk provides a perfect medium for the growth of bacteria, it is essential that bottle feeding equipment is sterilised for the first year.

Before sterilising, all equipment should be washed in a dishwasher or in hot, soapy water, with bottles scrubbed inside and out with a bottle brush. Teats should be scrubbed and cleaned with a teat brush and water squirted through them to remove all traces of milk. For mums who are expressing breast milk, the parts of the breast pump that come into contact with milk (e.g. suction cup) will also need to be sterilised before use. All equipment should then be rinsed in water before sterilising.


If sterilised bottles are not being used immediately, they should be fully assembled and used within 24 hours to prevent contamination.

Sterilisation methods

There are three main methods of sterilising: cold water, electric steam and microwave.

Cold water sterilising

  1. Following the manufacturer’s instructions, fill the steriliser with water and add the sterilising liquid or tablets.
  2. Completely immerse the equipment in the steriliser using the float tray to ensure it is totally submerged and there are no trapped air bubbles.
  3. Replace the lid and leave for at least 30 minutes (or as per the manufacturer’s instructions).
  4. Rinse items with cooled, boiled water before use, if necessary.
  5. Change the sterilising solution every 24 hours.

Electric steam/microwave sterilising

These are the fastest methods of sterilising and require no tablets, liquid or rinsing of items. They are more expensive to buy and may require regular de-scaling. Some microwave sterilisers don’t hold as many bottles as electric versions.

  1. Following the manufacturer’s instructions, add the required amount of water to the steriliser.
  2. Ensure that all of the bottle and teat openings are facing downwards in the steriliser so that they do not fill with water.
  3. Replace the lid.
  4. For electric steam sterilisers, simply switch on. For microwave sterilisers, place in the microwave using the correct power setting for the required amount of time.
  5. Allow the contents to cool slightly before opening the lid. Refer to the manufacturer’s guidelines to see how long equipment will be sterile for.
  6. Steam sterilisers need de-scaling, on average, once a month, depending on the hardness of the water. Microwave sterilisers may require occasional de-scaling.

Steam sterilising: an example of on-pack instructions

1 Wash hands thoroughly and wash the feeding equipment in hot, soapy water. Scrub the insides and outsides of the bottles using a bottle brush. Scrub the teats with a teat brush and squirt water through them to help remove all traces of milk. Rinse all equipment thoroughly under the tap.

2 Add the require amount of water to the steriliser (see manufacturer’s instructions).

Load the steriliser with the equipment, including the teat tongs (making sure that no items are facing upwards/able to fill with water). Put the lid on the steriliser and either switch it on or put it in the microwave on the required power and time setting (see manufacturer’s instructions).

4 When it has finished, the steriliser will usually turn itself off. Keep the lid on the steriliser and allow the contents to cool slightly before opening.

Always assemble the bottles using the sterilised teat tongs to avoid contaminating the sterile equipment. If not being used immediately, bottles should be fully assembled with teats and lids in place. Use bottles within 24 hours (see manufacturer’s instructions, as this may vary).


Next, read the article on storage of feeds.

Originally Published by Training Matters