I agree with Martin S. This is a poor design. My bottle leaks as well, but more importantly, the mount fell apart over a bump just as he described. I won't buy a replacement until the design is stronger and more durable. Not even sure a longer screw will help.
Nice Idea but it doesn't hold up. Water Bottle leaked every time I took a drink, but that was ok I have plenty of other bottles. The cage is held to the mount by 1 screw. The weight of a full bottle is too much for that 1 small screw and the screw is too short. The screw holding the cage onto the mount only goes 1/2 way or a 1/4" into the mount. That is not enough to hold a full bottle when you are on a rough road or hit bumps. Mine separated stripping the treads in the mount and scattering parts and bottle down the road. If you buy one, replace the screw with one that goes all the way into the mount.
The perfect accessory. Easy to install and very stable .....no vibration.