The Bottle Sling, Jug Sling, Indian Jug Knot, Hackamore, or whatever you want to call it, is an extremely secure way to put a handle on a water bottle. I've been using it for years, and have never had a bottle slip out when this knot is around the neck. I am using an old cotton shoelace in the video, but I prefer to use a length of paracord as it absorbs less moisture (useful for a water bottle holder). And the knot I use when I attach the two ends is a Lapp knot, without the quick release, but any bend should work here. Attach a carabiner to the bottle sling, and you've got a way to attach your bottle to the outside of your bag. Use different color cords, and differentiate between purified and unpurified water. Use a longer piece of cord and wear your water bottle over one shoulder. Bring your favorite beverage into the woods, secure the sling to something on shore, and drop the bottle into the cold river to chill it for a couple hours. And as a bonus, you can slip this knot off one bottle and onto another pretty easily. I use it daily for carrying a water bottle to work. Honestly, this is one of my favorite knots.