i am looking for replacement hydration tubing. i have been using clear "non-toxic" tubing from the hardware store, but it keeps developing a white powder on the inside. despite it's "non-toxic" labeling, i'm wary of using it anymore. we use our water sacks 200+ days per year, so purity is an issue.
i bought some silicone tubing from mcmaster's (as recommended on this form for water filtration system), but it fails as a hydration sack tubing, because it collapses when making the 180* bend out of the backpack. it's also soft and was abraded by the pack where the tubing went across the barbs of the cap fitting.
i looked around the mcmaster's site and they have many types of tubing, but i can't figure out the right type for water, and the right stiffness so it won't collapse. anyone have any ideas? thanks!

HomeDepot/Lowe's usually sells "food grade" tubing. I used 1/4 size to make a kegerator, and the same pliable tubing will work in your system. It can be purchased by the foot.