I have a Sweetwater Guardian, and I like it. It’s probably easier to pump than any other filter because of the lever it uses. I do know (from using at REI) that it pumps easier than an MSR filter with a similar lever. However, if I were buying a filter for the first time, I would consider an MSR Miniworks or Waterworks or a Katadyn Pocket Filter or Minifilter. The MSR filters attach directly to a water bottle (or my MSR Dromedary water bag), so there’s no output hose to get contaminated. The Katadyn filters seem to get the most use out of their replaceable filter elements, if their claims as to filter life are accurate. All of those filters have the requisite pore size (.2 microns, I believe) to filter out cysts, protozoa, and most bacteria. In any case, check out the monthly panel here about water filters and contaminants, or go to rei.com and find their chart that compares the abilities of various makes and models of filters, to make sure the one you buy removes the things from the water that you want it to. And remember this is only one opinion (mine) among many. You may place greater emphasis on other factors in choosing a water filter. A trick to extend the life of any water filter, which I probably read in this newsgroup, is to cover the “prefilter” at the end of the intake hose that goes into the water source with a coffee filter, to strain out the larger contaminants and keep them from clogging the filter element.
After living with intestinal distress for a long time, and driving ourselves insane trying to figure out what could have been causing it, we have finally fixed on tap water as the most likely cause. (We’ve known for a long time that the water here was hard — stains on the toilet attest to that! — and it may be that, or it may be something else.)
I’m off to Nepal to do some trekking soon and considering taking a water purifier with me mainly to ensure a safe supply of drinking water but also to do my bit at reducing the plastic bottle pollution epidemic. Can anyone recommend a good purifier that’s both compact and capable of producing enough clean water for two people for the duration of the Annapurna Circuit trek I’m reckoning on about a liter each a day for twenty one days. All I can say is, make sure you have some iodine tablets (and something to kill the taste) because you never know when the darn machine’s going to break.
I have a Pur Scout water purifier.
I am posting this info for anyone in the market for a portable water purification system. I know a guy who has designed and is marketing one that I am considering. He doesn’t have access to the net and I have no connection with this business, so please don’t write me about it. Here’s the general info:
We just bought a house that has well water. The sellers were all gung-ho about a system the house has where the water runs through a clear tube past a UV light (about the lenght of a regular fluorescent light). It is supposed to kill the bacteria. I am a Med Tech who has been working in Micro for 15 years and I am not impressed. Am I missing something here? I know UV light will kill bacteria and we use these lights in our hoods to decontaminate. However, I thought that this killing took a little time. These bacteria are going to just wash right past this light in a flash. Are they really zapped that fast? I was wondering what fellow Microbiologists think of this?? I don’t think it is worth replacing the $80 bulb once a year. The state water test certificate came back with no coliforms.
I am contemplating purchasing the Aquarium Pharmaceuticals Tap Water Purifier and would like to hear opinions people have of this product. Does it really work? I live in the Chicagoland area so the water is hard and basic, so I would like to lower the pH of my water to about 6.5-7.0. 



