Played my first game yesterday and we had the situation arise where there was no water left to fill up a new water tower because players were hoarding water. I couldn't find in the rule book whether the resources are supposed to be limited or not.
In order for the water to run out, there should be (roughly) about 8 on each player's Farm. That's almost 3 full Water Towers on EACH player.
Not saying that it can't happen, but are you sure this is the optimal way to go? There are obviously strategies where it is advantageous to have many Water Towers in your Farm (more than 3 at least and all full) but it rarely applies to more a single player at the table (at the same time).
Most of the time, having about 5-6 water tokens on your Farm is more than enough to cover your needs.