DIY Pack Water Bottle Holders
If you prefer to have water bottles attached to your shoulder straps for easy access, you can easily construct a pair of water bottle holders with some shock cord and cord locks. Use the shock cord and cord locks to construct two loops above and below the sternum strap, going through the webbing that the sternum strap slides up and down on. You'll find the Propel brand of water bottles have nice ridges that make this work well.
–Submitted by Dave Schultz