Re: Water Bottle filter

The filter bottles have their uses (doing the tourist thing, for example, where you are wandering about town or visiting a Famous Tourist Site, called sehenswurdigkeiten in German = "sights which must be seen"). The filter for the Katadyn bottle I just got has a capacity of about 200 gallons, so would be adequate for a month-long tourist trip that had day hikes. You could still refill the bottle out of local streams even in 3rd world countries.

For more extended trips, especially backpacks, a hydration bladder or several 1 liter bottles are better, in which case you need a different method of sanitizing the water - pump filter or chemical purification.

For cooking, you are going to heat the water anyway, so you really do not need a filter or chemical purification. The only thing you might need is a way of removing the crud (silt, sand, large critters). A bandana or "coffee filter" is adequate for that, or letting the water stand overnight, then decanting off the top, may be adequate (doesn't seem to be adequate for glacial flour, though - that seems to never settle out). Heating to 155F or higher will kill viruses, bacteria, and protozoa, no need to actually boil (then again, who carries a thermometer, so go ahead and raise the water to boiling).

As Ed G noted above, none of these will remove chemical contamination, like sulfur water or the runoff of industrial, agricultural, or mining wastes. These contaminants are molecules not a lot bigger than the water molecules, hence much smaller than the smallest 1 micron filters. As I have noted before, we have abandoned mercury mines in our local hills in the SFBay Area, with the fish in the streams so contaminated with mercury compounds that signs are posted along the trails and reservoirs "Do Not Eat The Fish!!!".