Exclusively breastfed babies start drinking water at six months. Exclusive breastfeeding, within six months do not need to specifically give the baby supplemental water, but there are abnormal situations also need to consult the doctor after hydration. 1. Within six months: breast milk contains a lot of water, so in principle, the water in breast milk can meet the water needs of babies within six months, without additional supplemental drinking water. However, if the baby loses more water, or there are respiratory infections, fever, gastroenteritis, vomiting, diarrhea, etc., according to the baby’s condition, under the guidance of the doctor to add water, so as to avoid the baby dehydration. 2. After six months: the general baby after six months to start adding complementary foods, at this time you need to drink the right amount of water to avoid constipation and indigestion, the amount of water depends on the baby’s diet and defecation. If you find that the baby’s urine is small, yellow urine, dry mouth or constipation, it means that the baby drinks less water, and need to replenish water in time. Whether babies add water is related to individual conditions, it is recommended to observe babies more often.