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.
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 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: 
I would like to know other’s experiences, both good and bad, with under-the-counter water filters. Specifically, I’d like to know what brand you purchased; whether you think you got your monies’ worth; and last, how difficult was the installation? I installed an Everpur brand filter this past weekend. Purchased it from Camping World for just under $90. It seems to work fine so far. Installation was somewhat complicated by the fact that I could not use any of the parts included for connecting into my water line. 
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. 
RE just started selling a gadget called “Steri-Pen” which is supposed to purify water using UV light. Pour 16 ounces of water in a jar, stir with the Steri-Pen for 40 seconds, and the UV light supposedly kills any harmful bio-organisms in the water. Chemical hazards aren’t affected, of course, but iodine and boiling are also ineffective against chemical poisons. The Steri-Pen weighs just 6 ounces including batteries and costs $200. 4 AA batteries will purify 140 pints of water. Does anyone have any experience with this gadget? Can it replace water filters and iodine for field use? It seems a whole lot simpler, as well as lighter weight than water filters. This is not an advertisement. I have not used this gadget and do not know if it works. Pretty cool. The science is sound. Doesn’t seem suitable to the backcountry though, I don’t use a glass. What they need to make is a 12″ UV tube for doing gallons, or at least pints (liters for our metric friends). But the battery pack would make this impractical, especially compared to an iodine tablet. If you have the time, would letting it lie in the sun all day achieve the same thing? Solar water purification? I saw this thing too. At this point I wouldn’t trust it to do the job but i think that definitely this is the way of the future for backcountry water purification. I can’t wait for it to be developed further. I think that It would work best in combination with some sort of a prefilter. but in order for that to make sense it would have to be a very light prefilter mechanism otherwise why not just carry your average water filter. Can anyone think of a devise that would work as a prefilter indipendent of a filter? Something like a coffee filter or cheese cloth rigged to some sort of light pumping device.
It just seems that everything I try to search they don’t have on the site. Why bother to pay for a subscription if they don’t even evaluate faucet-end water filters? So, I’m putting out the question here. I want to replace my countertop water filter (hard to find the filters). I’m considering something like an Instapure or Waterpic (not sure if these are the correct brandnames) to attach on the end of the faucet. I remember seeing an ad on TV once that showed the filter had a visible indicator when it was time to change. Anybody have one of these?
I’m thinking of buying an Equinox water purification device which hooks up to my tap. I heard about a T.V. news segment which showed that many such devices don’t actually work. The person selling me the Equinox product showed me a video which tried to separate this particular product from other devices in that it used a much more extensive carbon filter system and 2 other chemical removal systems which I can’t remember right now. He claims that it is state of the are in that it can remove virtually all organic compounds but keep beneficial minerals in. There is also a seal on the device saying ’Tested and Validated Under Industry Standards - Water Quality Association , S-200 ‘ .
