A canteen is a drinking water bottle designed to be used by hikers, campers, soldiers and workers in the field. It is usually fitted with a shoulder strap or means for fastening it to a belt, and may be covered with a cloth bag and padding to protect the bottle and insulate the contents. Many canteens may also include a nested canteen cup.
In Wasteland, this will keep your Desert Rangers from becoming dehydrated and taking damage in the desert.
Wasteland 2[]
While the canteen does technically exist in Wasteland 2, it can't be interacted with except filling it up.