I'm sure this is a minor point for you, but since you brought it up, I'll share what works for me: a Sawyer Mini water filter. They cost $15 to $25 depending where you shop and weigh 2 to 3 oz. You can fit one in your pocket. You can drink from a river, creek, or lake and not get giardiasis.

You can even put one inline in a hydration pack, so that you just fill the bladder from a creek and then drink through the hose, but I've never tried that.

I personally just carry mine in a pocket (when I'm riding out in the boonies) and refill my water bottle(s) as needed. I've been using one for years as a backpacker, and as a road cyclist in places where I won't find stores, like the North Cascades Highway.





As long as there will be water sources on the ride, and a good map will confirm that, you can carry less of the stuff knowing you'll be able to fill back up.