On Canadian canoe trips, I don't filter.  (I do, however, take a Steripen or filter "straw" for those instances where I might be in need of water when I'm in more confined space, e.g., stream.)  I'll generally take water from a deeper part of the lake on my way into a campsite for the night.  I scoop up a few gallons into a water bladder.  (Think a Base Camp filter, which I also have, but don't use any longer.  What I actually use is a dry bag from Cabela's with an air-bleed valve, which serves as a nice spigot in camp.)

But, for those of you that plan to filter, you should also be aware that you can get Giardia from activities other than DRINKING water.  So, be careful when bathing, washing your hands/face, washing dishes, etc.  While the volume of Giardia (and water) could be less, it stands a better chance of concentration near the shoreline where these activities are more likely.  This also means you need to pay attention to what happens to your clean/filtered water lines.  (Don't wash/dunk them in the water you are about to filter!)  When backpacking (e.g., U.S. Rockies), I keep my water lines in separate baggies, even though they go in the same storage bag.  So, be careful!

dd