If you see a water bottle backstage, please dispose of it.
I've found one too many just sitting on the floor back there, and it is sooooo easy to just kick one over or even worse, kick one onto the stage accidentally.
Someone even had one set on the floor behind the walls behind the fridge on the stage right side. Note to everyone, those walls have a gap under them due to the wheels. I was wondering if that was a water bottle gleaming under the stage lights at the foot of the wall last night. I was right. I could see that water bottle!
There were also water bottles left backstage on the heater, a few on the floor, one in a light fixture, and one on the prop cart (which better have been used as prop water because only props can be on the prop cart.
Sorry, I've asked you to pick up all water bottles, but it's just not clicking with some people.