When can babies drink tap water?
Guidance differs by country — Sips of water with meals from around 6 months. UK: unboiled tap water from 6 months. Australia: cooled boiled until 12 months. Formula water: always boiled
From around 6 months, once solids have started, babies can have sips of water with meals. In the UK that tap water does not need to be boiled first. Australia says cooled boiled water until 12 months. Formula is a separate rule everywhere: that water is always boiled.
The verdict
From around 6 months, when solid food starts, babies can be offered sips of water from a cup with meals. Before that, a fully breastfed baby needs nothing but breast milk, and a formula-fed baby needs nothing but their feeds, except small sips of cooled boiled water in hot weather.
Whether that water has to be boiled is where countries part company, and the gap is wider than most parents realise. The UK and Ireland stop boiling drinking water at 6 months. Australia carries on until 12 months. That is a six-month disagreement between two authorities with equally good public health systems, and neither is being careless.
Why water at all, and why so little
Water in the first year is a skill, not a nutrition strategy. The AAP puts it precisely: offering water in a cup from around 6 months helps develop cup drinking skills and familiarity with water, and the actual intake is unlikely to replace much breast milk or formula at that point.
That is the reason the amounts named are small. A baby who fills up on water is a baby who takes less milk, and milk is where the calories, protein, fat and, in formula, the iron are. Australian guidance makes the same point from the other direction: drinks other than water, breastmilk or formula in the first 12 months can stop a baby getting enough essential nutrients.
Under 6 months, and water intoxication
Giving extra water to a baby under 6 months, or watering down formula to make it stretch, is genuinely dangerous rather than merely unhelpful. Excess water disturbs the balance of sodium and other electrolytes in a small body, and the consequences described in paediatric guidance include seizures. This is why every authority says babies in the first 6 months do not need water in addition to formula or breast milk unless a clinician has specifically advised it.
Boiled or not: the actual argument
Boiling water does one thing: it kills microorganisms. It does not remove lead, nitrates or chemical contaminants, and as US guidance notes, boiling can in some cases concentrate them.
The UK and Irish position is that mains drinking water is treated to a standard where microbiological risk to a baby over 6 months is negligible, so boiling adds nothing except scald risk and inconvenience. The Australian position is more conservative about the first year in general, and keeps the boiling step through it.
Neither position applies to formula. Formula water is boiled everywhere, because the point there is not the water, it is the powder.
Cups, not bottles
Every authority that covers this says the same thing about the vessel, and it is worth as much as the water advice. A cup or beaker with a free-flow lid, without a non-spill valve, is better than a bottle or a beaker with a teat, because it helps a baby learn to sip rather than suck. From there, move towards an open cup as soon as your child is ready.
Nothing but breast milk, formula milk or water should go in a bottle or trainer cup, and nothing should be added to a feed, including sugar, cereals or baby rice.
When your tap water is not ordinary tap water
Guidance about tap water assumes a treated mains supply. Several situations fall outside that, and they change the answer.
Private wells, bores and tanks
Private wells are not covered by the regulations that govern municipal supplies. US guidance is specific: have well water tested for nitrates before giving it to infants under one year of age. High nitrate levels in well water cause methaemoglobinaemia in young babies, which is why this is singled out. New Zealand guidance keeps tank and bore water boiled for considerably longer than town supply.
Lead pipes
Lead enters drinking water from lead pipes, lead service lines, and brass fittings and solder, particularly in older properties. There is no known safe level of lead in a child's blood. Where lead pipework is suspected, running the cold tap before use, using only the cold tap for drinking and for feeds, and getting the supply pipe checked are the practical steps; boiling does not help and can concentrate it.
Water softeners
Softened water is higher in sodium and should not be used for making up formula. Most installations leave one unsoftened tap for drinking; that is the one to use.
How much, and in what
The amounts named for 6 to 12 month olds are small, on the order of a few ounces or half a cup across a whole day, and they are a ceiling rather than a target. A baby who wants none on a given day is not dehydrated; a breastfed baby in hot weather will usually feed more often rather than drink more water.
Offer it at mealtimes, in an open or free-flow cup rather than a bottle. Water in a bottle competes with milk feeds in a way water in a cup does not, and it delays the move to open-cup drinking that guidance in every country is trying to encourage.
Where guidance differs
The UK and Ireland: sips of water from around 6 months, and drinking water for babies over 6 months does not need to be boiled.
Australia: cooled, boiled water from 6 months, with fresh unboiled tap water from 12 months.
New Zealand: town supply water can be used from 6 months, but water from tanks or bore holes is boiled for much longer.
The United States: no universal boiling rule for drinking water, an emphasis on fluoridated supplies for dental benefit, and a specific instruction to test well water for nitrates before giving it to a baby under one.
If you are following advice from one country while living in another, follow the local one. These differences track local water infrastructure, not disagreement about babies.
The NHS says that once your baby has started to eat solid foods, from around 6 months, you can offer them sips of water from a cup or beaker with meals, and that drinking water for babies over 6 months does not need to be boiled first. Fully breastfed babies do not need any water until they've started eating solid foods. Formula fed babies under 6 months may need small sips of cooled boiled water during hot weather as well as their usual milk feeds. Water for making up formula is a separate rule and is always freshly boiled.
Showing guidance from NHS — read the source.
The HSE says to offer your baby water in a cup at meals or snack times, and that drinking water for babies over 6 months does not need to be boiled or sterilised first, while formula still needs to be prepared safely. It adds a specific caution about bottled water: avoid using bottled water labelled as natural mineral water, because it can have higher levels of sodium and other minerals. Breastfed babies, it says, do not need additional water even in hot weather or when travelling to hotter countries.
Showing guidance from HSE Ireland — read the source.
The American Academy of Pediatrics says that around 6 months you can start offering your baby a little bit of water in an open, sippy or strawed cup, and that if you live in an area where the water is fluoridated, drinking water will also help prevent future tooth decay. It sets a small daily amount for 6 to 12 month olds and notes that actual water intake is unlikely to replace much breast milk or formula at that point. Its separate water safety guidance advises having well water tested for nitrates before giving it to infants under one year of age.
Showing guidance from AAP — read the source.
Australia keeps boiling for longer. The Raising Children Network says that once your baby has reached 6 months you can start to offer cooled, boiled water in a cup at mealtimes and at other times during the day, so your baby can practise drinking from a cup, and that once your baby has reached 12 months you can offer fresh tap water without boiling it. Under 6 months, babies need only breastmilk or infant formula, and drinks other than water, breastmilk or formula in the first 12 months can stop a baby getting enough essential nutrients.
Showing guidance from Raising Children Network — read the source.
Sources
- Drinks and cups for babies and young children — NHS, accessed
- Introducing solids: why, when, what and how — Raising Children Network (Australia), accessed
- Recommended Drinks for Children Age 5 & Younger — American Academy of Pediatrics, accessed
- Drinks for babies 0 to 12 months — HSE Ireland, accessed
- Is Your Drinking Water Safe? — American Academy of Pediatrics, accessed
- Basic Information about Lead in Drinking Water — US Environmental Protection Agency, accessed