Many thanks all. I found a number for Katadyn-Canada (in Toronto -- nearby) and talked to a fellow there a little while ago. He confirmed what's been said here; if the filter was stored dry and is undamaged "it's good for the next twenty years". Also told me the "iodinized" purifier cartridge is no longer available in North America (health regs), but as noted above, the widely available "Hiker" microfilter fits the case. As noted in first post, it was indeed stored dry (barely used -- just a test when I first got it), and it certainly is working very nicely now. It will go with me and a friend canoeing for three days in Frontenac Park this weekend. Best, and thanks, jcp