We used the water bag for the past 3 trips in past 3 years.  We were initially really impressed.  Then about halfway through 8 night trip it slowed down to a dribble.  We took out the hand pumps.  (6 people)

Next year, 2 people.  Couldn't believe that this could happen again, had to be a faulty filter.  By the end of the trip, same thing.

Now here is the funny thing, you would think that at $50 per filter for the bag, a person would just go back to the hand pump, which seem to have the same flow rate for 2 plus trips.  However, this product is pretty cool!! We bought a second one (4 people).  Sadly, the oldest one sprung a leak about half way through the trip and by the end of the trip the 2nd one slowed to a trickle, it still trickled.  (It seemed, if memory served me, about 25 minutes to fill one nalgene). 

Since it costs $50 per filter, I am looking at the Platypus system, $109, the reviews at REI don't say anything about slow flow. 

Oh, by the way, I wrote to Katadyn about this.  They said that in Quetico the water has some type of microscopic slime that makes the filter clog up faster than normal.  In 30 years of going up and reading a  :-/lot, I never heard about this, but i did google at the time and there is such a thing, but alas, no reference to clogged filters. Frankly, I believe Katadyn created a very cool product with a very profitable water filter for them to sell.  Isn't capitalism great!  Hopefully some other manufacturer will figure out a better filter system that lasts longer.