For healthy infants in the US, breast milk or correctly prepared infant formula normally supplies the fluids needed before around six months. Do not add plain water routinely or dilute formula. An infant who seems dehydrated, is unwell, or is not feeding properly needs individualized advice, not a home water prescription.
Once your baby is developmentally ready for solids, usually around six months, offer a little safe drinking water in a cup alongside meals. The American Academy of Pediatrics describes roughly 4–8 US fl oz (120–240 mL) across a day for ages 6–12 months as a general guide, not a quota to finish or a replacement for breast milk/formula.
Important regional distinction: the NHS (UK) describes a hot-weather exception involving small amounts of cooled boiled water for some formula-fed infants under six months. That is not universal US advice. Water drunk separately and water used to mix powdered formula have different safety rules.
Key takeaways
- Before about 6 months, healthy infants normally need breast milk or correctly prepared formula, not routine plain water.
- At around 6 months with solids, offer a few sips in an open, free-flow or suitable straw cup.
- AAP/CDC 6–12 month example: about 4–8 US fl oz (120–240 mL) water a day; do not force a target or replace milk.
- UK NHS hot-weather advice under six months is a specific regional exception, not general US guidance.
- Never dilute infant formula; drinking-water and powdered-formula preparation follow different rules.
- In the US, no fruit/vegetable juice before 12 months, including diluted juice.
- Reduced wet diapers, unusual sleepiness, poor feeding or significant illness warrants prompt professional evaluation.
At a glance
Which drink fits each age?
Plain water for drinking is not the same as water used to prepare powdered formula. These are age-based general guidelines, never an individualized intake prescription.
| Age | Main milk | Water and cup practice |
|---|---|---|
| Before 6 months | Breast milk or correctly prepared infant formula | No routine extra water in the US; discuss any illness, hot-weather or dehydration concern with a clinician. |
| Around 6–12 months | Continue breast milk or infant formula as main nutritional drink | Offer small water sips with solids, and practice an upright, supervised cup. Cow's milk may be an ingredient in food but not the main drink. |
| From 12 months | Breastfeeding may continue; plain pasteurized whole cow's milk or an unsweetened fortified alternative (fortified soy is closest; no rice drinks under 5 in the UK) can be considered | Offer water and cup drinking with meals; avoid forcing an exact milk volume and keep meals varied, including iron sources. |
For US 6–12 month water intake, CDC/AAP guidance describes about 4–8 US fl oz (120–240 mL) per day as a general pattern, not a required amount to finish. NHS advice for some younger formula-fed infants in very hot weather is a country-specific exception; consult your clinician about any illness or hydration concern.
When can babies have water?
Before around six months, healthy babies generally get their fluid needs from breast milk or correctly prepared infant formula. Continue normal responsive feeds even when it is hot. In the US, do not routinely add plain water to a baby younger than six months unless a healthcare professional directs you.
The UK NHS notes that some formula-fed babies under six months may need small sips of cooled boiled water in very hot weather alongside regular feeds. This specific UK exception should not be presented as a routine US practice, nor as permission to dilute formula or offer large amounts.
From around six months when solids begin, offer small sips of safe water with meals in an appropriate cup. Milk remains the main source of nutrition through twelve months. Ask the child's clinician for a plan if your baby was premature, medically complex or feeding poorly.
- Under 6 months: normally breast milk or properly prepared formula only; ask a clinician about unusual hydration concerns.
- From about 6 months with solids: offer small amounts of plain water alongside meals.
- Keep breast milk or formula responsive during the first year.
- UK advice for hot weather under 6 months is a regional exception, not a universal water rule.
Why too much water can harm young infants
Giving unnecessary large quantities of water to a young infant can reduce milk intake and, in severe circumstances, dangerously dilute blood sodium (hyponatraemia, sometimes called water intoxication). A baby's small body size makes overfeeding water a particular concern.
Do not try to treat fever, diarrhoea, constipation or dehydration in a young infant by giving large amounts of plain water. Follow a health professional's assessment, especially if the baby is unusually sleepy, feeds poorly, vomits repeatedly or has fewer wet nappies.
Powdered formula must always be made with the exact measured water-to-powder ratio in the product instructions and relevant local safety guidance. Adding extra water changes both nutritional concentration and electrolyte intake.
- Large volumes of water can displace milk and disturb blood sodium
- Never water down infant formula
- Seek prompt medical advice for dehydration signs or significant illness
- Do not use large water drinks as a home treatment
How much water does a six-month-old need?
For babies 6–12 months, AAP and CDC guidance describes approximately 4–8 US fluid ounces (120–240 mL) of water per day as a general guide. Start with small sips and follow your baby's interest; this is not a minimum to force or an exact individual daily prescription.
If your baby is just starting solids, a few sips may be all they want. Breast milk or formula remains the main source of hydration and nutrition. Do not replace bottles or breastfeeding with water or try to make a baby finish a cup.
If your baby has a fever, vomiting, diarrhea, unusually few wet diapers, poor feeding or another illness, seek tailored medical care about fluid replacement. Large plain-water drinks are not an appropriate treatment for dehydration in a young infant.
- 6–12 months: AAP/CDC general water guidance around 4–8 US fl oz (120–240 mL) daily; not a goal to force.
- A few sips with a meal are a sensible starting practice.
- Do not displace the milk feeds that still matter through twelve months.
- Health conditions and possible dehydration require a clinician's individual advice.
Open cups, free-flow cups and bottles
NHS guidance recommends introducing an open or free-flow cup without a valve from around six months. Cup drinking develops a new skill: sipping rather than sucking from a teat.
An open cup may spill, and that is normal. Pour a small amount of water into a lightweight cup, help the baby hold it and tilt gently without forcing a drink.
Try not to rely on a bottle or valved cup containing sweetened drinks through the day. Bottles should be discouraged after the first birthday under NHS guidance.
- Introduce an open or free-flow cup from about six months
- Allow supervised practice and expect spills
- Do not force a cup or volume of water
- Avoid sweetened drinks in bottles or trainer cups
Water alongside solid foods
Offer small sips when a baby eats a solid meal, without turning water into a separate nutritional target. Do not use water to push down food if a child is having trouble chewing or swallowing; stop the meal and assess the preparation.
Some infants experience firmer stools as diets change. Water with meals fits routine feeding, but persistent constipation should be assessed rather than treated with large additional volumes.
Hot weather, activity, diarrhoea and fever can change fluid needs. Continue usual milk feeds and seek care if the baby is unwell or shows signs of dehydration.
- Offer small sips with meals once solids have begun
- Never rely on water to make a poorly prepared solid safe to swallow
- Do not promise water will cure constipation
- Assess unusual thirst or illness with a healthcare professional
Recognizing possible dehydration
Changes in wet nappies from your baby's usual pattern, a dry mouth, unusual sleepiness or fewer tears can suggest dehydration. No fixed number of nappies by itself reliably rules out illness or dehydration for every age.
During vomiting, diarrhoea, fever or poor feeding, the child's condition can change rapidly. Seek prompt professional advice, especially in very young infants. Emergency symptoms such as being difficult to wake or markedly unresponsive require urgent care.
A baby who normally feeds well on breast milk or formula usually receives fluid through those feeds. Do not replace them with plain water as a response to possible dehydration.
- Watch for fewer wet nappies compared with normal, dry mouth or unusual drowsiness
- Seek prompt advice for feeding difficulty, fever, vomiting or diarrhoea
- Severe lethargy or unresponsiveness requires urgent medical care
- Milk feeds should not be replaced with plain water
Tap, bottled and formula-preparation water
For small drinking-water sips after about six months, NHS guidance states that safe tap water does not usually need boiling. Check the safety of the local water supply and any country-specific advice, especially when travelling.
Water for making powdered infant formula is a different matter from drinking water: NHS safe-preparation instructions use freshly boiled water that is still sufficiently hot when mixed with formula powder. Simply boiling it, letting it cool completely and then mixing powder is not the same process. Follow the product instructions and local public-health guidance.
Bottled water is not automatically sterile or ideal for making infant formula and may contain more sodium or sulphate than tap water. Check guidance before using it for formula; do not infer suitability from 'natural' or 'spring' branding.
- Drinking water from a safe tap usually needs no boiling once solids start under NHS guidance
- Formula preparation follows separate strict hygiene, temperature and powder-ratio requirements
- Bottled water is not necessarily sterile or appropriate for formula
- Observe local water quality notices and medical advice
Why juice and herbal drinks are unnecessary
In the US, the AAP and CDC recommend no fruit or vegetable juice before twelve months, even if diluted. Young babies also do not need sweetened water, soda, sports drinks, flavored milk, fennel or herbal drinks.
The NHS says babies under 12 months do not need juice and, if given, to dilute it 1:10 and serve it only at meals; US AAP/CDC advise no juice before 12 months. When a baby is ready for solids, appropriately prepared whole fruit provides a more useful eating experience than fruit juice.
If you are considering a nonstandard drink because of constipation, fever or poor feeding, contact a pediatric clinician rather than using a sweetened or herbal drink as hydration treatment.
- No juice before twelve months under US CDC/AAP guidance, diluted or otherwise.
- Avoid soda, sweetened drinks and infant herbal teas as routine hydration.
- Use appropriately prepared fruit as a food, not as a juice substitute for water.
- Ask a clinician about illness or persistent constipation rather than offering extra drinks as treatment.
Frequently Asked Questions
Can a newborn have water during hot weather?
In the US, healthy infants under six months generally do not need plain water; offer normal responsive breast milk or correctly prepared formula and seek medical advice if you are worried about dehydration. The UK NHS describes a limited hot-weather exception for some formula-fed babies, but this is not routine US advice and formula must never be diluted.
When can I give my baby water?
Around six months, when your baby begins solids, offer small sips of water with meals from a cup. Breast milk or infant formula remains the main nutritional drink during the first year.
How much water can a six-month-old have?
AAP and CDC general guidance for babies six to twelve months refers to about 4–8 US fluid ounces (120–240 mL) per day. Treat this as broad guidance, not an individual goal to force. Many new eaters begin with a few sips at meals while continuing normal milk feeds.
Does water replace a bottle or breastfeeding?
No. Plain water does not provide the calories or nutrients in breast milk and formula. Continue milk feeds responsively and do not add extra water when mixing powdered formula.
Can my baby have juice diluted with water?
Not before twelve months under US CDC/AAP guidance. Diluting juice does not make it appropriate for infants. Use small amounts of plain water with meals and offer age-appropriate fruit as food.
Is water for drinking the same as water for making formula?
No. Formula preparation needs the exact product water-to-powder ratio and local hygiene, safety and temperature rules. Follow the formula label and current CDC guidance; do not infer formula-preparation temperatures from drinking-water advice.
Do I need to boil water for baby to drink?
Safe tap water may be appropriate for older infants taking small sips with meals, but water quality and local public-health directions matter. Formula preparation has separate rules. Ask a healthcare professional about special medical or regional circumstances.
What if my baby shows signs of dehydration?
Fewer wet diapers than usual, unusual drowsiness, dry mouth or poor feeding can signal a problem. Contact a pediatric professional promptly, especially with fever, diarrhea or vomiting; a baby who is difficult to wake needs urgent medical care.
Sources & References
This guide is informed by current guidelines from leading health organizations:
- ●NHS - Drinks and cups for babies and young children NHS
- ●NHS - How to make up baby formula NHS
- ●AAP - Choose Water for Healthy Hydration AAP
- ●CDC — Foods and Drinks to Encourage, Water 6–12 Months CDC
- ●CDC — Infant Formula Preparation and Storage CDC
- ●AAP — Recommended Drinks for Children Age 5 and Younger AAP
