I always use a water filtration system when I am away from tap water for more than a day. I have had Giardesis and it is not fun. I imagine few people die from it, but it is very unpleasant. I recall vomiting and experiencing diahrea at the same moment in time, which is awkward. I also recall having an unquenchable thirst. My energy level dropped way down, which can be problematic when you are either hunting or just trying to crawl down to your truck to call it quits.

Go to a backpacking supply store and look at the inexpensive, lightweight water filtration systems they have. REI is one such source that has a web presence. There are probably others also. Take a personal water bottle or two for each member of the party. Draw water for all water bottles in the morning and drink from them all day long. I usually just take a quart bottle for drinking along the trail in the high mountains, but the books advise you to drink more fluids than this to prevent dehydration at altitude and also avoid altitude sickness. At night, the same drill, draw enough water to cook with, to drink, and to clean the pots up afterwards. Don't let raw stream water get on anything.

It sounds like several people have gotten away with just drinking out of very high streams, but based on my experience I would rather undergo the minor hassle of pumping water twice a day to avoid any chance of having Giardesisi again.