Convenience charges are everywhere nowadays. I bought a $3 bottle of water at the DFW airport in Dallas a few weeks ago. I still feel like a chump when I think about it.
If you're at a rave, festival, or a concert or something and don't feel like paying $5-$20 for a bottle of water, which is how they make the majority of their income, tell a member of the staff (preferably an organizer [they shuffle around a lot and talk on walkie talkies]) that you were given some kind of pill and now you're feeling dehydrated. The last thing any place wants is a hospital run and any possible resulting lawsuit. If you get the right kind of person, they might even lift a couple of bottles for you. There are a lot of shady people out there so why not (sorta) profit off of the known existence of the scum that can be found in crowded public locations?