Here’s a photograph of my favorite Nalgene OTG bottle that as you can see I’ve slightly modified. I’ve been carrying short lengths of duct tape on my backpacking drinking bottles for a long time now, it comes in very handy in a pinch and my water bottle is typically always within easy reach unlike carrying one of those a little rolls of duct tape in with my first aid kit or goodies bag somewhere deep inside my pack.
The great thing about this simple little mod (you really just wrap duct tape around your bottle) is that the tape stays put no matter how long you leave it on your bottle and doesn’t even come loose with multiple washings – which is good and bad. I typically cut the tape into different widths (see the narrow white strip at the bottom) and use multiple colors to have extra options. Great for all manner of emergencies!