There's yet another cause for a leaky water bottle -- ferrets which like to wash their hands at them, or like to hold them open by jamming the ball up. We have had a number of washers over the years (a Howard Hughs of Ferrets?), and we've had two (one current) who enjoy piling food right below the bottle and then holding it open by jamming up the ball to get some wet food when they want a change of pace. [Posted in FML issue 2486]