Breastmilk is 88% water. Babies do not need additional water, even in hot weather. Too much water, especially in the first 9 months, can be dangerous.

Under 6 months, water can be dangerous:

• In the first days after birth, water may increase bilirubin levels (jaundice) and cause excess weight loss
• Fills baby up without adding calories, resulting in weight loss
• Makes baby less interested in nursing, which may delay milk coming in or prevent establishing an optimum milk supply
• Increases the risk of diarrhea and malnutrition

Older babies

• Too much fills baby up, sabotaging milk supply from not nursing enough
• Breast milk has the nutrition and calories babies need to grow – water does not.
• Breastmilk has all the water your baby needs, even in very hot weather.
• At 6 months, baby can learn to use a cup at the same time as starting solid foods. Giving a few sips of water a couple of times a day (no more than 2-3 ounces per 24 hours) is fine and can prevent constipation
• Breastmilk supplies plenty of fluids and older babies (9+ months) who breastfeed without restriction can get the fluids they need through breastfeeding. Some may need a little water with solids to prevent constipation (4-6oz/day).

If you feel you must give baby (6-12 months) water, offer limited amounts in a cup (not bottle) and only after baby has satisfied hunger with breastfeeding.