Why the method matters
Many parents are surprised to learn that powdered infant formula is not sterile. Even sealed tins and packets can contain small amounts of bacteria. The NHS method is designed to kill those bacteria by using water that is hot enough — 70°C or above — when it meets the powder.
That is why some shortcuts that seem sensible, such as making up bottles with cooled boiled water or preparing a day’s worth of feeds in advance, are not recommended. The steps below are the ones the NHS sets out.
Before you start
- Wash your hands and clean the surface you will use.
- Clean and sterilise bottles, teats and other feeding equipment. The NHS advises doing this until your baby is at least 12 months old.
- Read the instructions on the formula packet, and use the scoop that comes with that formula.
Step by step: making up a feed
- Fill the kettle with at least 1 litre of fresh tap water and boil it. Do not use water that has been boiled before. Bottled water is not usually recommended for making up formula.
- Leave the water to cool for no more than 30 minutes. This keeps it at 70°C or above, hot enough to kill bacteria in the powder.
- Pour the water into the sterilised bottle first, up to the amount given on the packet.
- Add the exact amount of powder using the scoop that comes with the formula, levelling it off. Do not add extra powder.
- Put the teat and cap on the bottle and shake it well until the powder has dissolved.
- Cool the bottle quickly by holding it under a cold running tap, with the cap on.
- Test the temperature on the inside of your wrist. It should feel warm, not hot.
The order matters: water first, then powder. Adding powder first makes it harder to measure accurately. Using the exact amount matters too: follow the packet and do not add extra powder.
Fresh feeds, every time
The NHS advises making up each feed fresh when your baby needs it. Throw away any formula left at the end of a feed rather than saving it for later.
Night feeds are where this is hardest. Some families keep the kettle filled with fresh water and the sterilised bottles, scoop and formula ready on a clean surface, so the steps are quick to follow half-asleep.
Never use a microwave
Do not warm bottles in a microwave. Microwaves can heat unevenly, creating hot spots that can burn your baby’s mouth even when the outside of the bottle feels fine.
Feeding your baby with a bottle
How you give the bottle matters as well as how you make it up. The NHS advises:
- Hold your baby close, in a fairly upright position.
- Let your baby take breaks during the feed.
- Never leave your baby alone with a propped-up bottle.
Bottle-fed babies feed responsively, just like breastfed babies, so watch for early feeding cues rather than following a strict timetable. Our answer on how often newborns feed explains those cues.
When several people make up feeds
Formula is often where shared care goes wrong: a grandparent learned a different method, a partner assumes cooled boiled water is fine, a babysitter warms a bottle in the microwave. Showing everyone the same steps avoids that.
A shared diary can also help everyone see when the last bottle was given and how much was recorded. Zaripo is being prepared to record bottle feeds with the time and the amount you enter, visible to family members with access after syncing. The amount is a record of that feed, not a target, and Zaripo does not recommend amounts, set feeding intervals or check how a feed was made up.
When to get help
Get urgent advice — contact a GP, health visitor or midwife, or NHS 111 in the UK — if:
- Your baby is not feeding well, is being sick a lot or has fewer wet nappies than usual. Talk to your health visitor or GP.
Outside the UK, use your local doctor, health line or emergency number. Trust your instincts: if you are worried about your baby, get help.
Questions parents also ask
Why does formula water need to be 70°C?
Powdered formula is not sterile. Water at 70°C or above kills harmful bacteria in the powder. Boiled water left to cool for no more than 30 minutes stays at that temperature.
Can I use cooled boiled water for formula?
The NHS method uses freshly boiled water that has cooled for no more than 30 minutes, so that it is still at 70°C or above. Do not use water that has been boiled before.
Can I use bottled water to make up formula?
Bottled water is not usually recommended for making up formula. Use fresh tap water boiled in the kettle.
Should I put the water or the powder in first?
Water first, then the exact amount of powder using the scoop provided, levelled off.
Can I make bottles in advance?
The NHS advises making each feed fresh when your baby needs it and throwing away any formula left at the end of a feed.
Is it safe to warm a bottle in the microwave?
No. Microwaves can heat unevenly and burn your baby’s mouth.