Chagul Water Bag
Chagal (Water Carrier), Canvas: British Army

This chagul has an NSN showing it is Canadian issue. These are new and unissued.  

NOTE: The classic chagul is designed to leak slowly so that the outside is always damp to provide evaporative cooling (and it works!)

More information;

Genuine Issue British Army

Tough & durable canvas material

Made like the classic WW2 version!

SAS/ LRDG

Made in the UK by CQC

The chagul, also known as a chagal, is a bag that is used to transport water; the bag is filled after soaking it, which keeps it temporarily watertight. The water slowly evaporates through the canvas fabric, keeping the liquid contents cool. Holds approximately four liters and is about 21 inches long.

Adopted by the British Indian colonial army from a traditional South Asian Indian form of carrying water, the chagul was used by the British military prior to WWII.