How to sterilise baby bottles: a complete guide for parents

Whether you’re exclusively bottle-feeding or combination feeding your baby, sterilising baby bottles (and all other feeding equipment you intend to use) is very important to ensure that your baby is healthy and protected from tummy bugs and infections like vomiting and diarrhoea¹. 

Below you’ll find lots of information about how to sterilise baby bottles, why it’s so important, and the different sterlising methods to choose from. We’ll also take a look at which equipment needs to be sterilised and when it’s safe to stop, as well as answering some of your commonly asked questions.

You probably know that sterilising baby bottles and other feeding and baby equipment is essential, but why is it so important? Well, it’s because, in some circumstances, milk can breed bacteria which can cause food poisoning². 

During their first year, your baby’s immune system isn’t as well-established as that of an adult. In fact, their immune system won’t reach full maturity until they’re around 14 years old³. This means your little one is more vulnerable to the bacteria that could make them ill. Sterilising baby bottles kills these bacteria and helps protect your baby from infections including vomiting and diarrhoea².

While sterilising baby bottles is essential, there are other bits and bobs (not just related to feeding time) that you’ll need to ensure are sterilised too (especially when your baby learns how to throw…). These include⁴: 

• Bottle teats, caps and rings. Many bottles come with various parts, including screw bottoms and anti-colic valves - these will all  need to be sterilised.  
• Breast pump parts. If you use a breast pump, you’ll need to sterilise each part that comes into contact with breast milk.
• Milk storage containers (including storage bottles, lids and cups).
• Feeding spoons and bowls.
• Dummies.
• Plastic teething rings – provided they’re labelled as boil or steam-safe.

In addition to the above, always make sure that you thoroughly wash your hands and any surfaces you’ll be using to prepare your baby’s bottle.

Before you sterilise your baby’s bottles, you’ll need to clean them first. While they may sound similar, cleaning and sterilising are two very different things. Cleaning your baby’s bottles removes any remaining milk or dirt, and you can’t sterilise without doing this first. Sterilising eliminates germs and bacteria⁵.

Let’s take a look at how to clean baby bottles before you pop them in the pan, microwave, or steriliser^1,6:

1. Wash your hands thoroughly.
2. Clean any surface you’ll be using with hot, soapy water.
3. Check all feeding equipment for any damage.
4. Wash bottles and teats in hot, soapy water, using a bottle brush and teat brush for hard-to-reach areas.
5. Clean all other parts of the bottle, including lids, caps, and suction rings.
6. Before placing the bottles and feeding equipment into the steriliser, rinse everything under clean, cold running water to remove any bubbles.

There are several methods you can use when sterilising baby bottles and equipment, and here we’ll take a look at the main 3:

• Steam sterilising. 
• Sterilising baby bottles using boiling water.
• Cold water sterilising.

There are two types of steam sterilisers: those that plug into the mains, and those that you put in the microwave.

To ensure that you use your steriliser safely and properly, always^{6, 7}:

• Follow the manufacturer's instructions.
• Fill the unit with the correct amount of water (as per the instructions), as this will create steam to kill any bacteria.
• Make sure that the openings on all teats and bottles are facing down when placed in the steriliser.

If you’re considering steam sterilising baby bottles, you’ll find that there are a variety of units available to buy. Some can be pretty bulky, so it’s a good idea to consider the space you have before investing.

You could choose to use self-sterilising bottles, which can be handy if you’re away from home or out and about. However, there’s nothing to confirm that sterilising bottles this way is as safe as the other methods we’re discussing here. If you do decide to use self-sterilising bottles, it’s very important to follow the manufacturer's instructions exactly².

Sterilising baby bottles using boiling water is very easy to do, and you won’t need any additional equipment - bonus! To sterilise baby bottles by boiling⁶:

• Check that the bottles and equipment are suitable for boiling.
• Boil your baby bottles and feeding equipment in a large pan full of water for at least 10 minutes (the majority of bacteria are destroyed when the water reaches 100 degrees Celsius²).
• Set an alarm to remind you to take the pan off the heat.
• Ensure all the equipment is fully submerged under the water’s surface.
• Regularly check teats for cracks and tears, as this sterilising method can cause them to become damaged more quickly.
• Never leave the pan or any hot liquid unattended.

When sterilising your baby’s feeding equipment with cold water, you can use a clean, watertight container or your steam steriliser, provided the instructions say it’s suitable. You’ll then need to⁶:

• Add a sterilising solution that uses chemicals (available in either liquid or tablet form) to  cold water.
• Check the bottles and teats for air bubbles (to work properly, the sterilising solution needs to come into contact with all parts of the feeding equipment⁸).
• Put the bottles and feeding equipment into the water, ensuring that every piece is fully submerged (if you’re using a steam sterilising unit, this will likely have a floating cover to help with this).
• Leave the feeding equipment in the sterilising solution for at least 30 minutes.
• Once sterilised, rinse all equipment with cool boiled water7.
• Change the sterilising solution every 24 hours.

Because your baby’s immune system isn’t yet fully developed, NHS and HSE guidance states that you should continue to sterilise your baby’s bottles until they reach at least 1 year^1,9.

Once sterilised, the clean baby bottles and teats can remain in the pan or steriliser until you need to use them.

Alternatively, you can remove them using clean hands or tongs, reassemble them, and place them in a clean area that has been disinfected. You can also place them on the upturned lid of your steriliser¹.

If you’re cold water sterilising, the solution will only remain sterile for 24 hours, so any equipment that you haven’t used within that time will need to be sterilised again before you feed your baby¹.

Steam sterilisers will come with manufacturers' instructions that you’ll need to follow, but as a general rule, most advise that you resterilise baby bottles after 24 hours².

Yes. When you buy baby bottles, they’re not sterilised and may have come into contact with dirt and dust during handling and transportation to the shop or warehouse. Sterilising will make sure that germs and bacteria are killed.

No, a dishwasher can’t be used as a replacement for the steriliser. While you can clean your baby bottles in the dishwasher, this will only clean them – they will still need to be sterilised after⁶.

This all depends on where you’re going and the kind of facilities you’ll have when you get there. You could take your electric or microwave steam steriliser with you or bring along a sterilising solution if you think you’ll need to sterilise using cold water.

Sterilise your bottles as close to your departure time as possible, and pack them in a sealed container so that you can use them while travelling.