The EPA (Enviromental Protective Agency) required Katadyn to submit to some very tough tests at University of Arizona Dept. of Microbiology before they would issue a registration number for Micropur in 2002.

Every word on the package was negotiated with and eventually approved by the EPA.

The news for those that don't like to wait 4 hours is: Micropur uses the most effective chemical registered by the EPA---Chlorine Dioxide at 4 PPM(parts per million) for killing all disease causing micro-organisms in water. In the EPA's cold dirty water test it took Micropur 4 hours to kill Cryptosporium Protozoa Cysts (eggs).

Cryptosporidium causes a two week bout of diarhea and other ugly symptoms, and is just as common as Giardia in water worldwide. A 1992 CDC (Center for Disease Control) study found Cryptosporidium, or Giardia, or both, in 97% of the streams sampled in the U.S.

If you are just worried about Protozoa and bacteria in your backcountry water: use any of the fine micro-filters from Katadyn or MSR to filter those out-----and have cold fresh, non-chemical water immediately.

I use Micropur as a back-up in case I lose,break or clog my microfilter. However, in trips to Nepal & S. America my group first pumped the water through a Katadyn Microfilter to remove the hard to kill with chemicals Protozoa (and bacteria as well): then added a single tablet of Micropur to each Liter of Water.

Virus that may cause incurable and deadly types of hepatitis are common in polluted water in those continents. Virus are much more susceptible to chemicals, and the EPA testing shows that even in cold dirty water all the virus are killed within 15 minutes: 1 tablet of Micropur per 1 Liter of water.

If in doubt: microfilter first, then add Micropur: wait 15 minutes and drink clear, safe, good-tasting water.

Went back and forth between these and other water purifiers and decided on these in the end...was not disappointed. After you dropped them in and waited for it to do it's thing, no foul taste and feel safe drinking the water. Only draw backs are it does reccomend waiting awhile before drinking the water and it is for a set amount for each tablet. I suppose you could get creative and say .5tablet for .5 liter...but who really wants to do math

Unlike iodine, kills all the nasties, yet doesn’t taste nasty. And unlike bottle forms of the same compounds, can just toss a few essentially weightless and individually sealed tablets in your pack for an overnight trip, as well as always keep some in your first aid kit. A piece of cheesecloth would be a good idea to filter out any debris before treatment. Only significant drawback is that this treatment would become fairly expensive on a per-liter basis.

When using the Katadyn Hiker and the Micropur tablets you can be assured of clean drinking water. I hike in some areas that have access to some poor water quality. I am not willing to take a chance on some viral contaminant. Using both a filter and chemical treatment can assure clean safe water.

Nice to have as a back-up. I'd rather carry a filter for my primary drinking water.

I tried these tablets on a recent jungle trip. I already had a heavy load, so the tablets saved me from carrying the filter... Or so I thought. I was very happy with the tablets, except for the fact that the wrapping says to wait 4 hours before drinking the water. I had thought it only took about 30 minutes, but not wanting to risk it, I waited the 4 hours every time. This was a pain because it meant carrying an extra bottle for the water to treat, which of course weighted more than the filter would have. I later found out that the 4 hour treatment is for very filthy water. So, the confusing label on the wrapping is responsible for me hauling that extra liter every day. The manufacturer should be more specific with the instructions. As far as taste is concerned I found them excellent.

I have never used these tablets but have used Sodium Chlorite (NaClO2) reacted with Citric Acid to produce Chlorine Dioxide (ClO2), which is a gas. This gas, produced after reaction, is the most effective pathogen (acid in nature) killer in nature known to man. ClO2 will not harm healthy intestinal flora (alkaline in nature) and works in the digestive tract even after pathogen exposure. Search the web for "MMS". Look past the 'health-nut hype' at the raw chemistry. I highly recommend any product that produces ClO2. Caution: Don't play with chemicals you don't understand! Use this stuff.

Keep these on hand as a backup. Just got back from Mt Whitney and my MSR Miox had dead batteries. We bummed some of these off some hikers and they were great. I'll keep some in my pack from now on.

I keep at least 10 of these packed in my 1st aid kit. The great thing is that they are individually sealed, so you don't contaminate the whole pack when you just need one. The packaging is tough (some would say too tough). A small nick with your knife prior to tearing open makes things easier. Have drank plenty of water after the 15min wait without problems. These saved a hike when the group filter broke after just one liter filtered.

Pluses: I find that water treated with MP1 tastes as decent as that treated with Aqua Mira, without the hassle of mixing chemicals and waiting the initial 5 minutes for them to react. I have also had Aqua Mira bottles leak on hot days when the pack was in the car going from low to high altitude (sea level to 10000 feet), though that may have been because they were in the sun all day. The amount is also easier to dispense with the tablets.

Minuses: Sharp foil packages, need to bend down the corners. Needs scissors to open.

Used it for the first time in N.C. Smoky Mts. on 4th of July weekend. I don't recommend using one tablet per 32 oz. Nalgene bottle (as it says in the instructions). This caused a very light chemical taste (not iodine, but more like chlorine). When I used a full liter of water (as it also says in the instructions), the difference was enough to cause a significant improvement. I must say that the water flavor was quite good. No stomach problems whatsoever after extensive 4 day use. I never used iodine tablets. I've always been a pump purifier guy, but if weight and convenience are a factor, I am taking these tablets on my next trip!

Maybe I didn't read between the lines, but once I got the tablets, I discovered that it takes FOUR HOURS to purify a liter of water! Who has the time to sit around and wait four hours before you can drink out of your water bottle? This stuff is less than worthless.

Knowing that only one person in our group (out of 7) was going to bring a water filter, I bought Micropur MP1 Tablets so that I wouldn't have to wait in line to use the filter.

We hiked four days in the Smoky Mountains and I used Micropur Tablets the whole time without any problems. In fact, at Clingman's Dome we filled up with water from the faucet and were surprised at how much more of a chemical aftertaste the faucet water had compared with the tablets.

Some people have complained about the price of the Micropur Tablets but for me, paying the extra money is worth not having to carry a water filter or taste iodine.

The water tasted great, but in use, 4 hours is just too long to purify a quart of water.

I bought these tablets because of widely available information on the net that they treat clear water in 15 minutes. Though the package says four hours, I'd been told it included instructions that the 4 hours was only needed when worries exist about cysts in your water source. New packaging omits any info about 15 minute treatments.

Regardless, this purchase was for a backup system for my Katadyn Hiker Filter, and I think they will work well for that purpose. A couple of tablets stored in my emergency kit give me the peace of mind (and my wife at home) in the back country.

Just used these on a camping trip and didn't notice the bad taste that others have complained of. This may be because I was drinking spring water from the mountains. Anyway, I'd recommend this.

I used Micropur MP1 tablets to treat water on a recent 4-day hike in the Tetons. Others in our group used a water filter. I think each method has its pros and cons, but I like the convenience of the tablets. They worked great since there is plenty of visibly clean, running water in the Tetons. We waited 30 minutes typically for treatment and had no problems at all with bacteria or viruses. The tablets do give the water a very slight change of taste, but it's quite subtle and not bothersome. We did not treat water for cooking since we boiled that. That helped to limit the number of tablets we needed to bring.

These are a good product for either backup water purification, or if you're a hardcore super-ultralighter. They leave more of a chlorine taste than the liquids (think drinking from a swimming pool), but this can be alleviated if you can leave the water bottle uncapped for a few hours. I like to use them at the end of the day, leave the bottles uncapped overnight, and the water tastes fine the next morning. I use them to supplement liquid chlorine, though.

While micropur tablets taste better than iodine, I nonetheless found that even after 24 hours water had an unmistakable-and potent-chlorine flavor. An improvement, to be sure, but not the revolution in chemical water treatment some would have you believe.

Took them backcountry recently, to kill viruses after using a filter, and found them to be excellent. I must live in a city with lots of chemicals in the water, because after that first "whiff" of chlorine when first opening the bottle after treatment, I didn't notice any smell or taste at all. Others in my party said they did notice a smell and a bit of taste, but they don't live in my town. We did wait at least 3 hours after treatment to use the water, just in case.

Really liked these tablets... used river water, virtually clean water, and let the tablets sit for thirty minutes. The description only says 20, but we did an extra ten just to be safe. :) No real after taste. Very good.

These tablets came in very handy. I typically prefer not to use chemicals, but I recently was camping in a remote area and both mechanical filters in our party failed. Without these tablets we would have really been in a bind. These are great to keep around in a first aid/survival kit, and should be taken as a compliment on any outdoor excursion.

On a recent trip in the Paria River in Escalante, both our filters failed, mine cracked, it was ceramic. We had been filtering then treating our water with these tablets for 2 days when we realized our filters failed. We were not too concerned about our water. All of us have not gotten sick and I have to truly thank this product for if we had not treated our water, we may have gotten ill. I now have a full supply for my day pack and my trekking pack for any backcountry adventuring I do. A necessary backcountry item you should carry in you emergency kit in your pack. Don't get caught out there with out them.

Light weight, easy to use. Three weeks after our backpacking trip down 2 slot canyons and no giardia. Filtered out the sand and bugs with a coffee filter and used the tablets as directed.There was no nasty after taste to the water.

I've gone backpacking several times and used these tablets... they definitely get the job done and they are good if you are on a budget. But I honestly prefer the other filters - they may be heavier and more expensive, but when you are in the backcountry and you want to drink now, it's worth the price.

I bought this product for the positive reviews and to have around for emergencies. I typically filter water but these are so light you can bring these as a backup. I use them to disinfect my filter after each one of my backpacking trips. Two tabs in a liter of tap water, pump it through my filter and I know it is clean for the next time I need to use it. Using them to clean my filter also helps me to rotate my stock so they never expire. Way better than iodine in taste, and portability.