There was a flat (dirt) track motorcycle race over the weekend down in Florida. Needless to say, it was stupid hot there. Some of the riders mentioned drinking Pedialyte or something with salt in it, because their bodies were not using the water they were taking in.
When I am out at Bonneville, I do something similar. I started drinking Propel instead of straight water. My body seems to 'use' the Propel better/quicker than straight water. It tastes better, too.