How to Sterilise Baby Bottles (NHS Rules, Every Method Compared)

Sterilising does not remove milk; it kills germs. Dried milk residue shields bacteria from steam, solution and UV alike, so the NHS routine always starts at the sink: wash bottles, teats and rings in hot soapy water as soon as possible after a feed, using a bottle brush for the inside and a small teat brush for the teat, then rinse everything in cold running water before it goes into the steriliser.

This is also where the dishwasher fits, and where it stops. The NHS is explicit that putting feeding equipment through the dishwasher cleans it but does not sterilise it, so a dishwasher cycle can replace the sink wash, but the steriliser step still follows. Teats, by the way, live longest washed by hand; dishwashers and boiling both age the silicone faster.

Check as you wash: a teat that is cracked, sticky or misshapen gets binned, not sterilised. Damaged silicone harbours germs in places no method reaches reliably.

Electric steam sterilisers are the workhorse choice and the one we would set up on the counter for the first year. They heat a measured shot of water into steam that fills the chamber, which is the property that matters: steam goes everywhere the air does, including down inside the bottles, so there are no shadowed surfaces. Cycles run roughly 5 to 15 minutes depending on the machine, the electricity per cycle is negligible, and a closed steriliser keeps everything sterile for around 24 hours per NHS guidance.

Microwave steam sterilisers do the same job in a vented box you microwave for a few minutes: cheaper, smaller, great for grandparents' houses, limited by the size of your microwave and useless for anything metal. Both types follow the same NHS instruction: use them to the manufacturer's directions.

The one bit of upkeep is limescale. Steam sterilisers kettle-fur like any boiler, especially in hard-water areas, so a periodic descale keeps cycles effective and the machine alive. Our steriliser guide ranks the current picks, with the steam-vs-UV decision covered honestly.

Cold-water sterilising is the old faithful: a tub of water with a sterilising tablet or solution (Milton is the name everyone knows), into which everything goes fully submerged for at least 30 minutes per NHS guidance. Push the bottles under so no air bubbles are trapped, use the floating cover or plunger to keep items below the surface, and change the solution every 24 hours.

Its superpower is needing no electricity and no machine: a lidded tub or even a clean bucket works, which makes it the method for travel, camping, hospital bags and power cuts. Items can stay in the solution until you need them, and NHS guidance says there is no need to rinse off the solution before use, though if you prefer to, use cooled boiled water, never the tap.

The trade-offs are time (30 minutes versus a 6 minute steam cycle), a faint chlorine smell some parents dislike, and the daily solution change. As the only method in the house it is perfectly adequate; most families keep it as the backup and holiday kit.

The zero-equipment method: a large pan, everything submerged, boiling for at least 10 minutes per the NHS, with nothing allowed to bob above the surface. It genuinely sterilises and it costs nothing, which makes it the right answer when you are caught short somewhere with a hob and no kit.

As the everyday method it has two costs. First, teats: the NHS notes feeding equipment damages faster with boiling, and it is the teats that go first, turning sticky and misshapen weeks sooner than with steam. Second, plastic bottles: heat is exactly what drives microplastic shedding in polypropylene, per the Trinity College Dublin research we cover in our glass vs plastic guide, and a rolling boil is as hot as home methods get. Boiling glass bottles is fine; boiling plastic ones daily is the worst combination on this page.

Fish everything out with clean tongs, not fingers, and assemble while hot-but-handleable on a clean surface.

UV sterilisers kill germs with UV-C light instead of heat, water or chemicals, and everything comes out dry, which is genuinely pleasant. Because there is no heat, they are gentle on plastics and silicone, and they sterilise things no other method can touch: soothers, teethers, toys, pump parts and anything that must not be boiled or soaked.

The honest limitation is physics: UV only treats what the light hits. Shadowed surfaces, and the deep inside of a narrow bottle is the classic case, may not get a full dose, where steam simply fills the space. Bulbs also degrade over time and effectiveness varies with build quality, so a cheap no-name cabinet is a gamble in a way a cheap steam unit is not.

Our verdict from the steriliser roundup stands: steam for the bottles, UV as the luxury second unit for dummies, toys and plastic you want to spare from heat. If the budget covers one machine, it is steam.

The NHS aftercare rules are short and mostly about not undoing your work.

• Leave everything in the closed steriliser until you need it. Contents stay sterile for around 24 hours; the worst place for a sterile bottle is loose on the draining board.
• Assemble immediately on removal. Fit teat, ring and lid as soon as a bottle comes out, so the milk-contact surfaces are sealed against the kitchen air.
• Hands or tongs. Wash and dry your hands before handling, or use the sterilised tongs most steam machines include, and work on a clean, disinfected surface rather than the sink edge.
• Do not towel-dry. Rubbing a sterile bottle with a tea towel re-contaminates it on the spot. Steam-sterilised kit assembles wet and that is fine.

And the finish line, per the NHS: keep sterilising all feeding equipment until your baby is at least 12 months old. Young babies' immune systems are still developing, and milk is the perfect growth medium for the bacteria that cause vomiting and diarrhoea, which is the whole reason this routine exists.

• Treating the dishwasher as a steriliser. The NHS could not be clearer: it cleans, it does not sterilise. Fine as the wash step, never as the whole routine.
• Microwaving bottles bare. A microwave without a proper microwave steriliser box does not sterilise reliably and wrecks teats. The vented box is the whole mechanism.
• Boiling plastic bottles as the daily method. Maximum heat into the material that sheds microplastics when hot. Boil glass if you boil anything.
• "Self-cleaning" claims and antibacterial washing-up liquids as a substitute. No sink product sterilises. Wash, then use a real method.
• No-name UV cabinets. Effectiveness depends on bulb quality and dose, which you cannot see. If UV appeals, buy a reputable unit and keep steam for the bottles themselves.