Water Purifiers

Purifiers remove viruses, such as Poliovirus type 1 and Rotavirus Strain SA-11, that can cause hepatitus, meningitis, and polio.   Wilderness medicine professionals recommend treating water for viruses as well as bacteria and cysts.
When you choose your portable water purifier, keep these things in mind:

Sawyer Point Zero Two

sawyer water purifier$150 - replacement cartridge: $0
Using the same holow fiber membrane technology as their filters, the Sawyer purifiers just have a 0.02 micron absolute pore size rather than 0.1 micron. This blocks smaller viruses, but does result in a slower flow rate of around .25 liter/minute. It works great as a gravity feed system in camp, but the actual purifier unit can be used inline in many different ways.
The million gallon guarantee makes the Sawyer practically irreplaceable.

General Ecology First Need

camping water purifier$90 - replacement cartridge: $45
It process from .5 to 1.8 liters/minute depending on who you ask and weighs 15 oz. General Ecology's purifier purifies with no chemicals! There are a bunch of bad reviews about it from 1999-2000 but much less now that it has been redesigned. For a chemical-free purifier, its a good price ($.33/gallon) as long as it does not clog up on you as it seems to have done for quite a few customers. There are also complaints about how difficult it is to pump and poor customer support.
It has a water bottle adapter, replaceable cartridge with a 125 gallon life, and pre-filter to help with clogging. The "Structured Matrix" filter cartridge has a 0.4 micron absolute pore size accompanied by a "broad spectrum moleculer capture" process and "electrochemical separations" that all work together to remove cysts, bacteria, and viruses good enough to be certified to meet the EPA standard for water purifiers.
Man, I know some pretty big words for being an outdoors dude, but the literature General Ecology has on their product uses some really big words and doesn't really seem to say much about how it works. But, they have a PDF document on this page that describes results of testing and the First Need did a great job.

Katadyn Exstream Bottle

katadyn exstream bottle$45 - replacement filter set: $33
A new type of personal portable water purification system. A sports water bottle with a built-in filter and ViruStat Technology to eliminate cysts, bacteria, and viruses - cool! Carbon eliminates odor and off tastes too. Easy to carry and simple to use, just take off the lid, dip it in the water, put on the lid, suck or squeeze out the water.
ViruStat uses penta-iodine resin to kill waterborne bacteria and viruses. It then employs an ion-release technology to greatly reduce residual iodine, and coconut-carbon scrubbers to further minimize any residue. The ViruStat cartridge is preceded by a replaceable 1-micron filter that removes at least 99.9% of pathogenic cysts. A prefilter is installed ahead of the cyst filter to remove sediment and organic contaminants extending the life of the cyst filter. The ViruStat cartridge, cyst filter, and prefilters are all replaceable.
For individual hiking or exercising, its great. It carries 21 oz. of water. For $5 more, the "XR" version is a bit bigger, holding 28 oz. but still not appropriate for use as a camp filter to get cooking water. It's not efficient to open and close the lid over and over to get a pot of water.
The cartridge can handle 26 gallons (100 liters) before replacement, so $33 for 26 gallons is pretty spendy.

MSR MIOX

msr miox purifier$130 - test strips: $17/50
MIOX stands for "MIxed OXidants" which is how this gadget works. This one is pretty cool - no pumping, maintenance, or iodine. You just add water, shake it, and press a button.

This creates a powerful dose of mixed oxidants, which is then added to untreated water, inactivating all viruses, bacteria, Giardia, and Cryptosporidium.   Since the MIOX Purifier just needs camera batteries and salt to operate, it’s maintenance-free, delivering more water, more easily than any purifier ever before. Well, that's what the literature says anyway.

What you really do is fill a container with your raw water - a liter, gallon, or more. Then, take your MIOX and put a bit of salt in one spot, then pour a bit of water in another spot, then shake it to mix them together. Then by pushing the button, you are delivering an electric charge that changes the mixture to a mixed oxidant solution. The more water you want to purify, the more times you have to mix the salt and water and push the button. A bunch of lights tell you if the mixture is too weak, too strong, or just right. When the solution is ready, you pour it into your raw water and then shake that container up. You can use a test strip to check that the water is correctly treated.   After 15 minutes, all the viruses and giardia are dead. After 30 minutes, almost all of the cryptosporidium are dead, but you need to wait 4 hours to make sure they are all goners.

Now, you have dirty water with dead stuff in it that's safe to drink. Personally, I see this as a terrific way to purify water before filtering it. The MIOX is just 3.5 oz. so I'd treat a gallon of water, wait 15 minutes, then pump it through my filter to remove all the dead stuff, tastes, and odors. Most filters would also remove any undead cryptosporidium too.

SteriPEN

steripen uv light$150
The only portable water purifier that uses ultraviolet (UV) light to destroy waterborne microbes. SteriPEN sterilizes clear water by destroying viruses, bacteria and protozoa — including Giardia and Cryptosporidium. It can use 4 lithium, NiMH, NiCad, or alkaline batteries, weighs 8 oz. including batteries, and can sterilize a liter of water in 90 seconds. The lamp is good for about 5000 uses.

The SteriPEN only works on clear water - so you need to run it through a filter first and then use this tool to inactivate any critters that made it past your filter. Good thing about this method is it introduces no chemical tastes.
The one concern I have with it is that the water being treated is poured into a container and then treated. That means there might be some water on the lip of the bottle and the lid that are not reached by the UV light.

This table shows filters and purifiers. Go to the Water Filters page for more filter information.

Maker Model Wgt
(oz)		 Flow
(qpm)		 Price Extra Cost
per
gal* 		Filter life
(gal)

Water filters

: eliminate protozoa and bacteria
Sawyer Squeeze 3.5 1.8 $50 .005¢ 1M
Sawyer Mini 2.0 1.4 $20 .008¢ 250K
Katadyn Mini ceramic 6.7 0.6 $79 $44 2¢ 2,000
Katadyn Pocket Filter 16.6 1.0 $179 $155 1¢ 13,000

Water filters + activated carbon

: eliminate protozoa, bacteria, bad taste
Katadyn Hiker 8.3 1.0 $56 $30 15¢ 200
Katadyn Guide 10 1.0 $80 $39 20¢ 200

Water filters + activated carbon

: eliminate protozoa, bacteria, bad taste, organic chemicals
General Ecology Microlite 7.0 0.5 $38 $17 $1.40 12.5
MSR SweetWater 7.2 1.3 $60 $35 18¢ 200
MSR MiniWorks EX 12.6 1.0 $80 $38 8¢ 500
MSR WaterWorks EX 15 1.0 $140 $38
$50		 8¢
25¢		 500
Katadyn Combi Filter 21.5 1.2 $145 $69
$9		 .5¢
7.5¢		 13,000
120

Water purifiers

: eliminate protozoa, bacteria, viruses
Sawyer Point Zero Two 20 .25 $150 0.015¢ 1M

Water filters + purifiers + "structured matrix"

: eliminate protozoa/bacteria, bad taste, organic chemials, viruses
General Ecology First Need Deluxe 13.3 1.8 $93 $36 29¢ 125
General Ecology Base Camp 64.8 high $557 $75 15¢ 500

Water filters + activated carbon + purifiers

: eliminate protozoa, bacteria, bad taste, viruses
Katadyn Exstream 7.4 1.0 $42 $30 $1.15 26
Katadyn Exstream XR 7.4 1.0 $45 $30 $1.15 26
MSR Sweetwater 9.9 1.3 $75 $35
$8		 18¢
10¢		 200
80

Pumpless purifiers

: inactivates protozoa, bacteria, viruses
MSR MIOX 3.5 n/a $130 $17 battery costs n/a
Hydro Photon SteriPEN 8 n/a $150 n/a 15¢ 1250
*Cost per gallon = replacement filter cost divided by gallons per filter
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