Originally Posted By: Ren
Don't understand why they didn't make the outer cup thing metal.

They had one made out of stainless, but it appears to be discontinued and I'm not sure why. At least you could use it to boil water if the filter broke. May be a niche in the market for a stainless steel cup that fits on the bottom of the bottle.

It's cool that the grayl is supposed to filter viruses, but I'm hesitant - not just because of it's low volume to size ratio, but because it's plastic and you're expected to lean your weight on it to filter the water. Several reviewers on amazon have complained about it breaking. It would be prudent to have a backup way to make water safe if one decides to use it.