When Can Babies Start Drinking Water? What About Hot Weather?

A warm Australian afternoon can make a very ordinary question feel surprisingly complicated: should you offer your baby some water? If your baby is only a few months old, the answer is different from the advice you would give a toddler racing around the backyard.

With spring moving towards summer, we wanted to put the Australian guidance in one place. Not a perfect hydration chart for every child, and certainly not a reason to count every sip. Just a clear explanation of what changes with age, what to do on hot days and when to get medical help.

Can babies drink water in hot weather? The short answer

This reflects the current guidance from Sydney Children's Hospitals Network, Raising Children Network and healthdirect. Advice for a child who is unwell, premature or has a medical condition may be different.

Why water is different for babies under six months

It is natural to think that a thirsty person needs a glass of water. But young babies are not small adults. Their kidneys are still developing, their stomach capacity is limited, and milk is both their food and their fluid.

Breastmilk contains plenty of water. Infant formula, when prepared exactly as directed, also supplies the fluid a formula-fed baby needs. Offering water to a very young baby can displace milk feeds and, in excessive amounts, disturb the balance of salts in the body. That is why current Australian child-health guidance generally says breastmilk or infant formula only until around six months, including during hot weather.

Some older Australian resources still use different wording for formula-fed babies. We have prioritised current guidance from children's hospitals, Raising Children Network and infant-feeding authorities rather than blending contradictory advice into a confusing compromise. If your baby has been given an individual feeding plan, follow the treating clinician's advice.

One number that is easy to misunderstand: Australian nutrient-reference tables list about 0.7 litres of total water intake for infants aged zero to six months. That is an estimate of water obtained from milk or formula, not a target for bottles of plain water and not an instruction to measure an individual baby's intake.

Breastfeeding or formula feeding when the weather is hot

If your baby is breastfed

Follow feeding cues and offer the breast more often if your baby wants it. Some babies take shorter, more frequent feeds in warm weather. The Australian Breastfeeding Association explains that exclusively breastfed babies under six months do not need additional water. Parents who are breastfeeding should also look after their own comfort and drink to thirst.

If your baby is formula fed

Continue offering correctly prepared formula according to your baby's needs and any advice from your health professional. Your baby might prefer smaller, more frequent feeds when uncomfortable in the heat. If you are concerned about whether they are drinking enough, contact your maternal and child health nurse, GP or healthdirect rather than changing the formula concentration.

Fluids are only part of the plan. Move to a cooler room, dress your baby in suitable light clothing, use shade and keep the sleeping area safely ventilated. Never leave a baby in a parked car. These steps matter even when your baby is feeding normally.

From around six months: introducing water without replacing milk

When solids begin at around six months, you can offer a little cooled, boiled water in an open or straw cup. The first goal is familiarity: learning how to hold a cup, coordinate a sip and enjoy water with a meal. It is normal for much of that early water to end up on the bib.

Breastmilk or infant formula should remain your baby's main milk drink until twelve months. You do not need to push a baby to finish a full bottle of water, and water should not replace a milk feed just because it is hot.

Raising Children Network recommends starting with small amounts of cooled, boiled tap water from a cup. An open cup can be messy, but the mess is part of learning. A suitable straw cup is another practical option when your baby is ready.

Water safety can vary by source. If you use rainwater tanks, a private supply or have been advised that your tap water is unsafe, follow local health guidance. For ordinary tap water offered to babies under twelve months, Australian child-health guidance commonly recommends boiling and cooling first.

How much should toddlers and children drink?

Australian guidance gives useful reference amounts, but they are total daily fluids from drinks such as water and milk, not compulsory plain-water quotas. Water in food also contributes to overall hydration. Requirements change with temperature, exercise, health and individual needs.

These are approximate Australian nutrient-reference values for healthy children, not treatment targets for dehydration. A child who is very active, sweating, feverish or unwell may need a different plan. See the Australian Nutrient Reference Values and the Royal Children's Hospital for context.

For everyday drinking, plain water is the simplest choice. Milk can still have a role in a balanced diet, but juice, cordial and sweetened drinks are not needed to keep children hydrated. Sports drinks are generally unnecessary for ordinary playground activity.

What if my toddler says they are not thirsty?

Young children often get absorbed in play and forget to drink. Some cannot reliably describe thirst yet. Rather than turning water into another negotiation, make it part of the rhythm of the day: a drink with breakfast, water with snacks, a bottle in the bag and another offer after running around outside.

A toddler might happily drink from a small cup at home but ignore a large heavy insulated bottle at childcare. The most useful bottle is the one they can lift, open and drink from safely. We would prioritise an age-appropriate spout, easy cleaning and a size that suits their hands over a fashionable brand or an oversized capacity.

If your child is drinking vastly more than usual or seems constantly thirsty, especially with increased urination, seek medical advice rather than assuming it is only the weather.

Signs of dehydration: what to notice

The first useful comparison is with your own child's normal pattern. Are they feeding as usual? Having their usual wet nappies or toilet visits? Alert and interested in what's around them?

Possible dehydration signs include fewer wet nappies or wees, darker urine, dry mouth or lips, unusual tiredness, sunken eyes and reduced activity. The Royal Children's Hospital explains that more severe dehydration can include cold hands and feet, mottled skin and marked lethargy.

Do not rely on a single symptom or a precise nappy count to diagnose dehydration at home. Babies with suspected dehydration, especially those under six months, need prompt professional assessment. If a child cannot keep fluids down, is unusually drowsy, has very little urine or seems increasingly unwell, seek urgent medical care.

Dehydration after vomiting or diarrhoea is different from ordinary thirst on a hot day. An oral rehydration solution may be appropriate, but the correct approach depends on the child's age and condition. For young babies, get medical guidance rather than improvising with water, juice or home-mixed drinks.

Water cannot fix an unsafe hot environment

We sometimes talk about hydration as though it is the entire solution to summer heat. It is not. Babies and small children can overheat in cars, hot bedrooms, poorly ventilated prams and outdoor spaces with too little shade. A full drink bottle does not make those situations safe.

Plan outdoor play around conditions, choose shade, allow rest breaks and make indoor spaces cooler where possible. For babies, use an appropriate pram canopy and maintain airflow rather than covering the entire pram opening with a loose cloth. For sun protection, follow Australian UV guidance separately from temperature advice.

Our earlier baby sunscreen guide explains why shade and clothing are particularly important for very young babies. Sunscreen and hydration solve different problems; neither replaces the other.

What works in real family life: childcare, cups and reusable bottles

At childcare or kinder

Ask how often water is offered and whether your child needs to bring their own labelled bottle. For toddlers who cannot ask for a drink, a regular opportunity matters more than waiting for a verbal request. A useful question at pickup is not just whether the bottle is empty, but whether staff offered water during meals, outdoor play and warm periods.

Choosing a bottle you will actually keep using

For a child old enough to use one independently, look for a manageable weight, a comfortable drinking opening, a lid they can operate and parts you can take apart and wash. Stainless steel can be durable and keep drinks cool, but many stainless bottles still have silicone seals or plastic lids. We prefer being transparent about that rather than calling a mixed-material bottle 'plastic-free'.

Check the manufacturer's minimum age and cleaning instructions. Some insulated bottles are intended for children aged three and over; they are not automatically suitable for a six-month-old learning to drink. If you already own a practical, safe bottle that your child likes, you do not need a new one because summer is coming.

If you are looking for a replacement, you can browse the Hello Charlie kids' water bottle collection. This is an optional convenience, not a medical recommendation.

Cleaning matters more than the material slogan

Water bottles are handled all day, often dropped in bags and sometimes left partly full. Wash the bottle and drinking parts according to the manufacturer's instructions, clean inside straws and seals where possible, rinse thoroughly and let components dry before reassembling. Replace damaged parts and do not assume a bottle is dishwasher-safe unless the maker says so.

A reusable bottle only works as a sustainable choice if it remains practical enough to use and clean. Buying three complicated bottles that nobody wants to wash is not the goal.

Three common misunderstandings

“It's hot, so my newborn needs a separate bottle of water.”

Not routinely. For a healthy baby under six months, breastmilk or correctly prepared formula is the usual answer. If your baby is feeding poorly or showing signs of dehydration, seek clinical advice promptly.

“My toddler needs to drink a whole litre of plain water.”

The familiar one-litre guide for ages one to three refers to fluids, not a required litre of plain water on top of milk. Food contributes water too. Think in patterns, not quotas.

“If the water bottle is insulated, the child can't overheat.”

Cool drinking water is helpful, but preventing overheating still means shade, rest, suitable clothing and avoiding dangerous heat exposure.

A simple hot-day check before you leave home

Frequently asked questions

Can I give my three-month-old boiled water when it's 35°C?

Current Australian infant-feeding guidance generally advises breastmilk or correctly prepared formula only under six months, even in hot weather. Boiling water does not remove the risk of displacing milk or disturbing fluid balance. If your baby seems dehydrated or is not feeding well, seek prompt medical advice.

Can a six-month-old drink tap water?

From around six months, offer small amounts of cooled, boiled tap water in a cup. Continue breastmilk or formula as the main milk drink through the first year. If your water supply has special safety issues, follow local advice.

Should I give extra water instead of formula on a hot day?

No. Do not replace a young baby's milk feeds with water or dilute formula. Continue age-appropriate feeding and seek guidance if you are concerned about intake or dehydration.

How much water should a two-year-old drink?

Around one litre of total fluids a day is a common Australian reference for ages one to three, including water and milk. It is not a compulsory one-litre plain-water target, and needs can be higher during heat or activity.

Is juice better than nothing if my child refuses water?

For ordinary daily hydration, water is the preferred drink. If your child is ill, refusing fluids or becoming dehydrated, the appropriate rehydration strategy can be different; speak with a health professional rather than treating juice as a general solution.

How can I tell whether my baby is dehydrated?

Look for fewer wet nappies than usual, poor feeding, dry mouth, unusual sleepiness or other changes in behaviour. No single sign is definitive. A baby under six months with suspected dehydration needs prompt medical assessment.

Do I need an expensive insulated bottle for my toddler?

No. A safe, clean, age-appropriate cup or bottle your child can use is more important than insulation or branding. If you buy a new bottle, check its age rating, weight, lid parts and care instructions.

Related reading

For another Australian summer safety question, read Can Babies Wear Sunscreen Under 6 Months in Australia?. For school-day routines, see Starting School the Healthy, Low-Waste Way.

At Hello Charlie, we think the useful answer is often the simplest one: age-appropriate drinks, a realistic routine and a little more care on hot days. Not another complicated rule for families to follow.

Sources and fact-check notes