Returning to the Well Again
Progress Through Technology?
Water Purification Brought Up to Date
By Farwell Forrest
August 8, 2006
[W]hat we call "Progress" is the exchange of one Nuisance for another
It's hard to warm to a cynic, I admit, but
Havelock Ellis may have gotten hold of an important truth here. In an ideal
world you'd never have to ask if the water under your keel was
potable. You'd know it was, and you'd just dip your cup and drink your
fill. But this paradise is now well and truly lost if it ever existed,
that is. Today, the only safe rule of thumb for anyone worried about drinking
the water is the well-known Fletcher Principle: If in doubt,
doubt. And then disinfect.
So much for general principles. The devil, as we're reminded almost daily, is
in the details. Fair enough. Just how can canoeists and kayakers make
sure the water they drink won't make them sick? Since any trip that takes you
farther than you can paddle in one day pretty much rules out carrying bottled
water from home the stuff is heavy, and active people need
to drink often if they want to keep going this is a very important
question. And I've tried to answer it before, most recently in "Returning to the
Well: The State of the Mart," an article that appeared on these pages almost
four years ago to the day. Of course, four years is a pretty long time, a point
that wasn't lost on one reader, who wrote in May to suggest that I revisit the
topic. He then drew my attention to the "excellent [ultra]micropurifiers on the
market now that filter down to the 0.02 micrometer level," and noted in
conclusion that if I hadn't been keeping up on the subject, I was sure to be
He certainly got my attention. No one likes to be out of date, after all, and
I'm no exception. I enjoy pleasant surprises, too. So I immediately went in
search of a portable ultramicrofiltration system, the Holy Grail of backcountry
water purification a filter whose pores are small enough to trap the
tiniest of waterborne bugs, but which is also field-maintainable and
sufficiently compact to stow belowdecks in even the smallest kayak. To everyone
who's struggled to keep a run-of-the mill microfilter free from clogging
sediment in the untidy world outside the laboratory, this will sound like a
formidable engineering challenge, and I guess it really is. To make a long story
short, I searched in vain. I found residential and commercial
ultramicrofiltration systems, to be sure, but nothing that a paddler could carry
along into the backcountry. Still, my reader made an excellent point. I hadn't
been keeping up. It was high time that I reviewed the state of the mart again.
And I did.
Here's what I found. First, the good news: every system mentioned in my
original article is still available, including one portable filter, the First
Need® Deluxe Water Purifier, that claims to remove viruses. (This, by
way of reminder, is where most microfilters fall down. They hold back
bacteria and protozoan pathogens, but the much smaller viruses simply slip
through the net. "Size-exclusion" microfilters, in other words, do only half the
job of disinfecting water.) But the Deluxe is an unusual filter. It doesn't rely
on pore size alone to exclude viruses. Its pores are no smaller than those of
other microfilters, in fact it is not a 0.02-micrometer
ultramicrofilter. Instead, the Deluxe makes use of the phenomenon of adhesion.
As one research paper puts it, "a combination of hydrophobic and electrostatic
interaction" on the surface of an activated-carbon Structured Matrix captures
and retains any viruses present in the raw water. Sceptical? I was, at first, to
be honest. But the test results look good. Very good. And even the most
case-hardened skeptic has to defer to fact. On the strength of the evidence
presented in the peer-reviewed literature and accepted by the US Environmental
Protection Agency, the Deluxe delivers the goods. End of story.
This is old news, however. As I've already mentioned, the First Need Deluxe
was discussed in my earlier article, and to some extent it anticipates my
reader's letter. It may not be a true size-exclusion ultramicrofilter, but it
is a filter. If the cartridge is replaced regularly, no additional
chemical germicide should be needed to make suspect water safe to drink. Is this
the Holy Grail? It looks like it to me.
OK. Let's move on. What's new? Quite a lot, as it turns out. Three novel
approaches to water disinfection caught my eye. I'll take them one at a time.
Nothing embodies progress quite like high-tech circuitry, right? And maybe
you've been hankering to carry a personal chemical treatment plant around in
your pocket. If so, you're in luck. The MSR MIOX® Water Purifier
uses an electrical current to break the chemical bonds in a small amount of
brine, yielding a potent cocktail of "mixed oxidants" (mostly chlorine
compounds, apparently). Once added to raw water, this MIOX cocktail renders
pathogenic bacteria, viruses, and protozoa harmless. Even the notoriously
resilient cryptosporidia succumb, though only after four hours' contact
Does this sound too good to be true? It's not. Developed for the US
Department of Defense, the MIOX apparently does what it claims. At a price. The
upfront cost is around US$130. Steep? Yes, but still US$70 less than the
venerable ceramic Katadyn® Pocket Filter, and the Katadyn does nothing
about viruses. Of course, high-tech circuitry means batteries (two CR123 lithium
cells, in this case), and you'll have to replace these every so often: MSR
suggests that treating 50 (US) gallons will exhaust a fresh set of cells. If this
is correct, figure on an operating cost of something like 26 cents a gallon
of treated water, unless you can find a bargain on batteries.
Cautions? Don't spill the mixed oxidant solution on your clothes or gear.
Carry plenty of spare lithium cells on long trips. And if you distrust
electronic gadgetry as much as I do MSR's reassurance that "the
electronics of the MIOX Purifier are as reliable as a cell phone or GPS unit"
fills me with a creeping dread consider bringing a back-up method for the
day when Nemesis
Minor gripes? I find the treatment process rather fussy. You have to (1) fill
the electrolytic chamber with raw water, (2) cap the purifier and shake it 10
times (or more), (3a) check a chart to determine the number of button clicks
required and then (3b) press the button the requisite number of times, (4) mix
the resulting oxidant cocktail with the raw water you wish to disinfect, and (5)
test the final product for free chlorine using the safety-indicator strips
provided. Whew! Still, practice should soon make this seemingly complex drill
almost automatic, I suppose. If you're worried about cryptosporidia, however,
you'll also have to wait four hours before you can drink the water, so plan
ahead. Lastly, don't use MIOX-treated water to make coffee. In
MSR's words, it imparts "a strange taste." Then again, you boil your coffee
water, don't you? And boiling kills bugs. Problem solved.
Recommendations? The MIOX Purifier is the answer to a technophile's prayer.
It also gives you a lot to talk about around the campfire, while you measure,
fill, shake, click, mix, and test. But don't expect all this to come cheap.
Next, let's look at the other end of the fussiness spectrum. It's hard
to imagine an easier way to treat water than dropping a tablet (or
two) in a canteen, shaking, and waiting ten minutes or so before drinking. That
helps to explain the enduring popularity of Potable Aqua® (tetraglycine
hydroperiodide, or TGHPI) germicidal tablets, despite their high per-gallon
cost and other limitations. (See my earlier
article for a detailed discussion.) But science marches on. Katadyn®
MP-1 Micropur Purification Tablets offer all the convenience of TGHPI and
more besides. While TGHPI can't be depended on to kill encysted giardia or
cryptosporidia, chlorine-dioxide-releasing Micropur Tablets can and do,
though, once again, a four-hour contact time is needed to ensure that any
cryptosporidia have gone belly-up. (They're tough little buggers.) Moreover,
chlorine dioxide doesn't taint water to the extent that iodine-releasing TGHPI
does, particularly at the higher (8-16 ppm) TGHPI label doses used by prudent
And the price for all this? Ah, yes. The price. You had to ask. Progress
doesn't come cheap. Figure on paying US$1.80 for each gallon of treated water.
But at least the upfront cost is limited to the price of a 30-tablet pack:
around US$14. That said, it's important to keep these things in perspective. I'll bet
you drink bottled water at home. How much does this cost?
Cautions? Don't buy more than you need for one season, and check the expiry
date on the package when purchasing. The shelf-life of Micropur tablets is
limited to two or three years. And don't remove tablets from the blister pack until
you're actually ready to treat some water. Never repackage Micropur
tablets, either. They lose potency fast when exposed to air.
Minor gripes? The blister pack isn't easy to open. If you've been looking
for a use for the scissors on your Swiss Army
knife, you've just found one.
Recommendations: Simple. Safe. Effective. What more could you ask from any
water treatment method? Cheap? Hmm.
Sorry. Nothing's perfect. But Micropur
Tablets come close.
And now for something completely different. The final advance I encountered
when reacquainting myself with the state of the art in water disinfection is
really a step backward to a simpler time. Back in the day, I had an uncle who
supported several wives (and many children) by dealing in used cars. Some of the
cars that he sold had less than immaculate pedigrees, I'm afraid, but he wasn't
a habitual villain. Mostly he bought wrecks at auction, got them running
again, repainted them, and sold them on. He didn't extend credit, and he didn't
offer much of a guarantee. On the other hand, his prices were low. Very low. He
had his share of unhappy customers, of course, and when one of them brought a
car back or, more often, pushed it back onto the lot my
uncle would invariably promise to fix it. After all, he hated to say no.
(Remember all those wives?)
Remarkably, he was a man of his word. When he promised to fix a car, he meant what he
said. First, though, he parked the dead car on the lot for three days, and then
phoned the purchaser to tell him it was ready for pick up. That was all. He
called this happy expedient the "sunshine treatment." Amazingly enough, it
frequently worked. More often than not, when the buyer came round to collect his
car, it started up right away and then kept running at least long enough
for him to get it back home. This was good enough for my uncle. He
didn't rely much on repeat customers, either in business or marriage.
What does all this have to do with water treatment? That's easy. It turns out
that one of the simplest ways to disinfect raw water is
the selfsame sunshine treatment. Just park your water bottle
in the sun. And wait. Sunlight more accurately, ultraviolet radiation
between the wavelengths of 320 and 400 nanometers, or UVA inactivates
most pathogens. Of course, no one calls this the "sunshine treatment." It's
known as Solar Water Disinfection, or SODIS for short. Originally
developed to meet the needs of rural villagers in what used to be known as the
Third World, SODIS also holds great promise for canoeists and kayakers,
particularly those paddlers who find themselves returning again and again to the
world's great subtropical and tropical regions, either in fancy or in fact.
Sound interesting? I thought so. You won't find SODIS gear listed in any
catalog, however. Why? The only equipment you need is a set
of one- or two-liter plastic soda bottles (PET, or polyethylene terephthalate bottles,
are best, and they must be clean, clear, and colorless), along with such
efficiency-enhancing options as a lick of black paint, a plastic dishpan, and
some aluminum foil. Want to know more? Just visit the SODIS website (www.sodis.ch). It should answer all your
questions. In fact, it's so good that I won't go into any details here. You'll
find complete instructions at the SODIS site. If you're curious, that should be your
next stop. I will add a few words by way of summary, however.
Cost? Minimal. You probably have all you'll need lying around your house
already. What's an empty soda bottle worth? Five cents in a state with a deposit
law, maybe. Cheap enough.
Cautions? SODIS requires sunlight. It therefore works quickest when the
weather's clear, more slowly on cloudy days, and not at all during prolonged
sieges of rainy weather. Furthermore, it's not for paddlers who are heading up
North: it's most effective at latitudes below 35 degrees. Since it's best not to
agitate water violently during the treatment period (six hours under optimum
conditions), it also requires a bit of forward planning.
Recommendations: Are you looking for a low-tech alternative to costly or
complicated high-tech water purification systems? Do your travels take you
equatorward? Then SODIS warrants serious consideration, if only as a backup (or
supplement) to your primary water treatment system. It never hurts to
have two strings to your bow, does it?
Progress. To paraphrase an old advertising slogan, it's humankind's most
important product. But there's a very different way of looking at things,
summarized in another old saying, one attributed to the French writer Alphonse
Karr: Plus ça change, plus c'est la même chose. The more things
change, the more they're the same. And we've seen an example in the preceding
paragraphs, when one of the latest wrinkles in water treatment turned out to be
something as simple as putting your water bottles on the deck to soak up some
rays. Who says there's nothing new under the sun? Not me, at any rate. And that
really is a pleasant surprise!
Copyright © 2006 by Verloren Hoop Productions. All rights