Basic points you consistently either miss or blatantly avoid are already addressed by the subsequent poster, but since you direct name calling at me personally, I'll throw in my 2 cents as well...
I'm not familiar with the Berlin setup. How hot are the conditions under which these barrels of water are sitting? How much use by the field do they get? How many barrels do they have at each station? How many people make use of these barrels? How do they make use of them, sticking their own cups in them? Dunking their sweaty hats? Rinsing their sweat-dripping hands in them?
Why you keep repeating this without explaining HOW you or anyone else is supposed to definitively know how much is 'enough' is beyond me. Simply repeating that mantra doesn't support your argument to any further degree and suggests some kind of close-mindedness.
What formula would you, as race director, use before the race to determine whether or not you had 'enough' water? Apparently in hindsight we know how much water 25,000 runners in very hot and humid conditions need, but HOW would YOU have figured it out BEFORE the race?
For that matter, suppose you were omniscient and knew what 'enough' was but discovered 30 minutes prior to start time you didn't have that amount. Would YOU as race director, have walked out in front of 35,000 people and said "thanks for coming out, but just grab your stuff and go home" or "every third person will be pulled off the course since we only have 'enough' water for 25,000 of you"?
I am comparing two situations where there will be a sizable expected demand for a popular product but no magic formula for experts in the field to determine exactly what that demand will be. If you can not understand that fundamental issue, just say so and I'll try and re-phrase that sentence in a more basic manner. Calling me names just demonstrates a an inability to construct a coherent counter-argument.
Most people would assume that when they see an advertisement for a new shoe, that the advertising store would have it in stock. Just as most assume when a race talks about water stations, that there will actually be water at those stations.
Both operations have people who are responsible for predicting the demand, ordering enough product (shoes or water) and then getting it in sufficient quantities to the front lines (individual stores or water stations).
You want the race to have 'enough' water. They could do that by pulling out all the stops and having Olympic sized swimming pools at each station. But that ain't practical or even feasible.
Customers want to be able to buy a pair of shoes when they come into a store, not be told to go somewhere else, or come back next week when there may be some in stock. The store could bring in hundreds of pairs of each size of each model to ensure that no one wasn't able to buy an advertised shoe, but that isn't practical or feasible too.
By your own logic, any idiot could be a shoe buyer and ensure that 'enough' shoes were available, just like any idiot could have ensured that 'enough' water was available at each and every water station.