Animals do that out of a sense of SELF-preservation. That was my point. Sorry about that. I already dealt with this in part. No one on the African plain wants to live near the predators.
Predators come to the watering holes.
If you don't believe this then build a house near a water hole and see how comfortable you about going outside. Thus they would not set up camps near the water. This requires that the Homo erectus comrades carry water some distance. As Walker and Shipman pointed out, this means they had a recepticle for carrying the water. I am aware of no such example.