I have used mine a lot, with clear water followed by a boil or a puri tab all the way to a stagnant horrible pool of liquid followed by a boil, the millbank excels because of it sturdy design, you dunk it in, get it soaked, let the initial run off wash the muck of the out side then fill the billy, scrub the inside of the bag and its ready for the next time, it can take the rough handling that is required so as to not be at danger of failing if dropped full or cleaned roughly while out for a while.