How Much Water Should a Baby or Toddler Drink?

By age

• Under six months: no additional water needed. Breastmilk or formula provides all hydration, including in hot weather.
• Six to twelve months: small amounts with meals — on the order of a few ounces a day total — offered in an open or straw cup. This stage is as much about learning to drink from a cup as it is about hydration.
• Twelve to twenty-four months: roughly one to four cups a day, alongside whole milk.
• Two to five years: roughly one to five cups a day, varying with activity and weather.

Cups, not bottles

Introducing an open or straw cup from around six months supports oral-motor development and makes weaning off bottles considerably easier later. Prolonged bottle use past the first year is associated with dental issues and with drinking more milk than a toddler needs, which displaces food.

Signs of dehydration

Contact your healthcare provider promptly if you see these, particularly during illness with vomiting or diarrhea, when fluid losses climb fast in small bodies.

• Fewer wet diapers than usual, or dark, strongly smelling urine.
• Dry mouth, or crying without tears.
• A sunken soft spot on the head in a young baby.
• Unusual sleepiness, floppiness or irritability.