So long as you have a second water container, or something to put the stuff in if you need the bottle, I say go for it. A good polycarb is hard to break, is water tight, and just can't die. A coworker of mine kayaks, and it turns out he keeps a 14oz wide mouth full of firestarting gear, PA tabs, SAK and a few odds and ends in a pocket in his life jacket and tethered to him in case he and the kayak have a parting of ways.