Why babies can't drink water? - Here's why

Water intoxication:

The average human adult is made up of 55 to 60% water. The average baby, on the other hand is made up of 75% water. And that's the reason why baby shouldn't drink water before they are atleast 6 months old. Our kidney have small capability to hold that much of water. Hence, the water that cannot be stored by our kidneys passes into our bloodstream where it dilutes the salt or sodium in our blood. Once our blood dips below 11g of sodium per gallon, we are at a condition called hyponatremia. It actually happens when our cells tries to return sodium levels to normal by absorbing extra water and swell up like a water balloon in this process causing complications like confusion and vomiting. Hyponatremia is common in marathon runners who drink too much of water too fast without also providing an extra sodium to balance out their blood. When we drink too much of water, it moves into our brain and causing water intoxication. It is noted that 2,00,000 Americans per year suffer from water intoxication. It causes swelling of brain, seizures and brain damage and lead to death. Child can't store as much of water that humans can. Their kidney size is half of the adults and also their filter rate is slow. Hence, most infants dies due to water intoxication as the kidneys can't filter the water and they reach the brain. So, when a child shows the symptoms of intoxication, we have to take them hospital and they provide intravenous saline solution to bring infants sodium level up to normal.