CF Waterproof bag
A waterproof bag is recommended for NATO participants. Expect rain, fog and other types of wet weather. You need some moisture protection for your gear. Bring a that is large enough to protect your sleeping bag, plus a change of clothes. Your waterproof bag should fit neatly in the large compartment of your ruck sack, keeping the contents dry when you are forward deployed. These are easy to get, and are inexpensive.
Canadian Forces specific waterproof bag information
There were no issued "waterproof bags" in the Canadian Forces, and while some troops may have been lucky enough to acquire one of the USGI ones, most troops typically used a heavy gauge garbage bag.