Here's what MSR reckon.
Completely collapsible for optimal packing efficiency, our burliest medium-to-large capacity water storage and delivery systems are perfect for everything from alpine- to road warrior-style expeditions. Armed with incredibly tough 500 and 1000-denier Cordura® exteriors and laminated with a BPA-Free and food-grade polyurethane lining, our Dromedary Bags can handle freezing and just about any kind of abuse you can imagine. Accessories like the Shower or Hydration Kits add do-all versatility.
Heavy-Duty: Abrasion-resistant Cordura®, laminated with food-grade polyurethane, can handle everything from freezing to boiling.
Versatile: 3-in-1 cap lets you fill, drink, and pour with ease.
Easy to Fill: Low profile, ergonomic handle and wide-mouth opening for no-hassle filling.
No-Hassle Attachment: Perimeter webbing allows for convenient pack attachment and hanging.
Safe Drinking: BPA-free
The most frequently described downside of these things as that they have a plastic taste and I agree. A fix reported online is to dose them with denture cleaning tablets or soak them repeatedly in a bicarb solution and rinse generously. While not entirely successful, I found it did help. I view these bags as safety water. Who cares if it tastes dodgy if you're seriously in need of a drink?