I have a Platypus system in my rucksack ; it's really very convenient to drink while walking, just a few sips every 10mn or so.
No more need to stop every half hour, to remove the sack and get the bottle out, drink, put the bottle back in the sack and the sack back on my own back .....
Still, I keep an aluminium waterbottle in a side pocket of the rucksack. As a reserve and as a backup : if I fall on my back, the plastic tank of the PLATYPUS system may burst under the induced pressure. The aluminium bottle should withstand the shock.

And it seems a good idea to use it inside a car : less dangerous than manipulating a bottle - of water or soda, of course - while driving.


Alain