This instructable shows you how to clean the mildew, mould and accumulated dirt from the plastic hose on your CamelBak or other hydration bladder with nothing but some paracord (and some optional sterilization tablets).
I discovered this neat trick an hour before setting off on a climbing holiday after finding that my CamelBak hose was disgustingly dirty.
Being loathe to spend £20 for a brush on a wire to clean the hose and without time to get one I looked around for something that could clean the hose.
Paracord was the answer! A loose knot in the end of a length of paracord, dropped through the hydration bladder's hose can be drawn through slowly and bring all the gunk with it.