Many races locate their water stations at or near a mile split point. The thinking is that runners and volunteers can be told easily where the station will be.
There's a downside, though. With all the commotion and activity at a station, runners may miss the split point, especially if it's only marked on the road. Second, their natural reaction when seeing the split is to look at their watch and hit the split button. The result is usually disasterously wet if they're carrying a cup of water, or worse, GatorAde, in either hand.