It is not easy because carrying a bottle or drum in your hand is something uncomfortable and impractical that will eventually lead to fatigue.
If we plan a tour that has one or several fountains with water, it is perfect because we will only have to make a small stop and continue with our training. But this is not a good solution for those who go running and do not want to stop.
Carrying a Camelbak on top is a good solution, especially in the case of small backpacks of one or two liters (although there are models with much more capacity for longer exits), which allow us to carry an adequate amount of water for an exit of several kilometers.
The only problem they have is the fact of having to wear them hanging on their backs, since they can cause us to sweat in that area and, in case they don’t go well and move, the race technique can be modified.
Perhaps the solution that seems most successful is to wear a bottle cage. We can adapt the size of the drum to our water needs and, being close to the center of gravity of our body, it will not be an extra exaggerated effort (only as if weighed half a kilo or a kilo more) and will not change our excessive running technique. Waist bags like these there are many, you just have to choose the model with which we are more comfortable and more suited to our needs.