This water storage bag is included in many US military aviation survival kits.  The Size A bag, available here, holds up to 5 quarts of drinking water.  It can also be used to store items that need to be protected from salt water, or inflated for use as a flotation aid. These bags are intended for use as short-term emergency water storage, and are a step up from the entry-level Whirl-Pak bags commonly included with survival kits.

Features:

• Can be rolled up or folded for easy, compact storage.
• Roll-top closure with strap/buckle fastening. 
• Integral belt loop for easy carry on belts or packs.
• Conforms to MIL-B-8571D specification. Factory certificate of conformance available on request. US Military NSN: 8465-00-485-3034
• Manufactured from Food Grade Vinyl Chloride, a material known to the state of California to cause cancer.