We use these for our water purification system.
A single tablet will treat 1 liter of water, so we need two each time we fill our platypus.
We've experimented with tiny water filters, aqua mira and iodine tablets. These win for me hands down.
First, I don't have to squat for 45 minutes pumping a cubic inch at a time to get my water, nor do I have to mess around mixing chemicals, and finally there's no weird after taste like with iodine – so no need to carry gatorade powder to hide it.
The MicroPUR tabs are based on Chlorine Dioxide (which I believe is what municipal water treatment plants use for your home), and so can even treat giardia, but you have to leave them for 4hrs to do that. We usually let them run for 30 minutes which kills most things.
The first time I used them, we had a bag of really cold water collected, dropped the tabs in an they started smoking as they reacted with the water, releasing a strong chlorine odor. It was a little disconcerting, but after 30 minutes the odor and taste had gone completely.
This system works for us, because where we hike we are mostly guaranteed access to good water – streams, lakes or rivers. If I was planning a trip where I had to use murky or sketchy water, I'd bring my filter again.
Three sheets of them weighs in a less than 1 oz..
The obvious downside is cost. It is not the cheapest way to treat your water, but hey – the cost of going Ultralight? Priceless.
Available from Amazon for $12.95.
These tablets kill Giardia in 30 minutes. However, it is 4+ hours for Cryptosporidium, a nasty amoeba.
From Katadyn: “Destroys viruses and bacteria in 15 min., Giardia in 30 min. and Cryptosporidium/i> in 4 hrs.”
A pump is going to remove all of the above. After our pump clogged on the JMT we used these tabs for 5 days and waited the 4 hours; this meant I carried 3+ liters of water most of the time, which was a real pain. Neither my wife nor I agree the tab treated water was tasteless – there was, in my opinion, a distinct chlorine taste and we were very happy to get back to our pump.
Worst of all, 3 or 4 of the tabs were duds (i.e. no fizz, no slight discoloration or chlorine odor typical of the other working tabs)
I keep two packs of these (20 tabs) in my kit as backups, in case my main water purification fails.
I use the SteriPen (heavier than tabs, lighter than filters) to sterilize 99.9% of bacteria, viruses, protozoan in 1L of water in 90 seconds. It pretty much requires a wide mouth bottle too, which makes this a bulkier & heavier option. No added funky chemical tastes.
REI says that filters don’t kill viruses, and Iodine doesn’t kill Cryptosporidium.