You may wonder if it's OK to give your baby water, or if your baby needs it, especially in the summer. The answer is no. During the first year of a baby's life, you don't need to supplement formula with bottles of water--even on hot days. In fact, giving infants water can be dangerous because they can easily suffer from water intoxication, a condition in which their developing kidneys can't excrete water fast enough. As a result, water builds up in the body and dilutes the electrolyte balance of the blood, which can cause seizures, coma, or even death. Give your baby a little extra breast milk or formula instead of water if you sense that she's thirsty on especially hot days.