[pct-l] lightwight water purification on the PCT

[Trekker4 at aol.com (Trekker4@aol.com)]

  There's a new water purification method: high tech, but expensive at first 
glance. It's called Steripen, a uv light; it's 8 oz,  with 4 lithium AAs in it 
and 4 spare lithium AAs; and it kills everything. That's about half the 
weight of any standard purifier system. 
    Modern nickel metal hydride batteries may give about the same number of 
treatments, but 4 nmh batteries weigh 1 oz ea, like alkalines, instead of the 
1/2 oz ea for lithiums. The weight of the Steripen and 8 nmh batteries would be 
12 oz; plus see the discussion below about chargers. The cost of nmh 
batteries is far lower, so the cost per gallon would be lower.  
    I've tried First Need, PUR (now PUR-Katadhyn-sp ?), and Sweetwater; I've 
had problems with all 3, mainly fine silt. The Sweetwater worked best, with a 
prefilter and a coffee filter over the intake debris screen, but with spare 
parts and extra prefilters it weighed 16 oz.
    The Steripen will purify 5,000 pints, 2,500 quarts, or 625 gallons before 
the uv light must be replaced; the unit costs $150, about twice a standard 
purifier system; so, the cost per gallon for a new Steripen is 24 cents, about 
the cost of water out of a grocery store reverse osmosis machine. A replacement 
bulb costs $60, so that's 9.6 or 10 cents per gallon. At this point, bear in 
mind that 625 gallons is about 2.5-3 thru hikes of any trail; to put it 
another way, that's possibly 500 days of hiking. 
    Rechargable batteries purify about 140 pints, 70 quarts, or 17.5 gallons; 
lithium-ion batteries purify about 100 pints, 50 quarts, or 12.5 gallons. 
I've always thought rechargables a bit iffy on a long hike, plus one has to carry 
a solar charger (a fair amount of weight) or a lot of batteries; lithiums are 
1/2 oz ea; regular alkalines are 1 oz ea. 
    Let's use lithiums to figure battery cost; at Sam's, 12 lithiums are 
$21.65 including tax, which is $7.22 for 4 lithiums or .0722 per gallon. My sales 
tax is 8.25%; your sales tax may vary, of course.
    That means with a new Steripen, the cost per gallon is .24 + .0722 = 
31.22 cents per gallon. A replacement uv light makes the cost of the next 625 
gallons = .10 + .0722 = 17.22 cents per gallon; I didn't try to spread the initial 
cost over any more that the life of the first bulb; the unit itself should 
last indefinitely, so there's no way to amortize that cost.
    A small, stainless steel, mesh prefilter that fits a Nalgene wide mouth 
bottle is coming in Dec or Jan, to filter larger stuff out of water that's "not 
clear". I've talked to them about that phrase, and it's still a bit nebulous. 
I'm just going to use a coffee filter for now, and maybe forever; coffee 
filters are extremely lightweight, dry quickly, and burn quickly.
    Lastly, the Steripen comes with a hard plastic protective cap that snaps 
over the bulb to protect it. When one uses the unit to purify, the water must 
be agitated; that the unit must be helf tightly against the canteen neck while 
rotating or moving with the uv light is on. I found an o-ring at my local 
hardware store that makes an almost snap in tight fit in the neck of the 1 quart 
fruit juice bottle I may use on the PCT for a canteen. My old Oasis, green 
canteen is only 1 oz more, so I may stay with it; I'd just have to hold the 
rubber neck of the Steripen against it while agitating. Neither seems difficult, 
and possibly could be done while walking.
    I'll be trying the Steripen in Big Bend National Park and/or Big Bend 
Ranch State Park in Nov and Dec. I'll try to remember to report back. I 
absolutely love the 3 benefits: less weight, less hassle, and especially less time to 
purify water, well under 10 minutes per gallon, possibly some of that while 
walking.
      
A long email, but definitely a new way to clean your water
Bob 
Big Bend Desert Denizen
(Naturalized Citizen, Republic of Texas)