How long does Katadyn Micropur MP 1 really take?

4 hours is the contact time required to purify cold water (39 ºF / 4 ºC), that is, to kill viruses, bacteria (E. Coli…), and cyst (Cryptosporidium, Giardia…)

The contact time to kill bacteria and viruses is 15 minutes, and to kill cyst in mild water (68 ºF / 20 ºC) 30 minutes (clear water).

If you use an additional filter (e.g. Aqua Mira Frontier Pro) wich takes on the "bigger and harder to kill" stuff, you can cut down the treating time to 15 minutes. Also, the filter helps to reduce sediments, taste, chemicals and turbidity. Treating time depends mainly on concentration and temperature. Also, certain circumstances can reduce the effectivness of tablets, for example small particles and turbidity. Therefore, when you only use the tablets, wait as long as you can, but at least 15-30 minutes (you won't be 100% safe tho).

Resurecting and old post/subject here.  My group goes back in forth with Katadyn Micropur Tablets and a Platypus Gravity Filter System for water on the trail.  I prefer Katadyn Tablets.  Packs smaller and much easier to use- not that the Platypus is that hard.  For the tablets, I’ve always just given them an hour and been fine.  Directions on box says four hours.  Am I tempting my luck by only letting tablet work one hour…three less than recommended?  If I had to wait four hours, I would go back to the Platypus and/or a Sawyer Squeeze.

All the information on chlorine dioxide treatment is out there for you to google.  Time x concentration curves and log reductions.

Nothing is 100% safe.   Its all relative reduction.  99.99, 99.999, 99.9999, etc.

EPA requirements to be called a water purifier……require huge reduction in highly tainted water…10e-5 to 10e-6. Water quality that you’re unlikely to ever encounter in the backcountry.

Viruses and bacteria are effctively  killed in a minute

Giardia……reduced 1000 fold in 15 minutes. when you consider you’re probably only going to get a concentration of a few cysts per liter, how much reduction do you need? 25% of people also are already infected with giardia asymptomatically, so theres that.

Cryptosporidium is the tough one….4 hrs…..Nobody ever waits for it, and nobody ever has any problems.   It’s just really not an issue in backcountry water.  If drinking cattle runoff……wait.

Treatment efficacy depends on time x concentration.  2 ppm for 8 hrs is equivalent to 4 ppm for 4 hrs is equivalent to 8 ppm for 2 hrs.  You can always use more or less and affect the treatment times needed as well.   Which is  reason a lot of people use AM drops

Thanks, MB.  I did do some research after posting the question and found much of what you posted.  Cryptosporidium is the one thing that kept popping up and thankfully it doesn’t apply when backpacking- at least it hasn’t yet.  We usually give the tablets an hour, which judging from what I’ve read is plenty.

30 minutes for me.

I’m a fan of the Frontier Pro coupled with AM drops (when I’m not using my UV purifier).  As noted above, the Frontier Pro filters out all the big stuff, and the AM kills all the small stuff in just a few mins.

I carry tabs as backup these days.  But generally dont use AM anymore, pretty much use a sawyer.  Water tastes better, I drink more without mixes.  Worth 4 oz + evernew bag.

Using AM, id add drops and keep hiking,start drinking 10-15 min later . Some water gets carried for hours anyway, and some overnight too.    Only time it matters is if your out……and really thirsty.  Id drink older water first most of time.  Using a couple of dasani bottles, not hard to keep track of.   My pack is light enough im not worried about carrying a liter of water unneccessarilly.

Sawyer mini is too slow. On first half of CT it cost me about an hr per day filtering.   Thats 2 mi.  Adds a couple days to  the hike……Switched to full size sawyer in Salida.  Not looked back.

Slightly off-topic, but somewhat related: I am a huge fan of the Platypus GravityWorks activated charcoal filter.  I place it in-line, post-filter to my gravity system when needed.

The water available on one of my favorite Atlantic barrier island destinations has a reasonably nasty sulfur taste and this addition completely eliminates that.  I have used it in other situations as well and it never fails to improve the taste.  An additional expense and bit of kit/fuss, but in certain conditions well worth it.