A Larger Problem
Good as gravity‑feed microfilters are, they have two shortcomings. As I've already noted, they're fussy, requiring periodic backflushing and protection from subfreezing temperatures, as well as requiring rather time‑consuming setup rituals. This is easy enough in camp, but it's a real pain if you just need a quick drink underway. And the second drawback? Viruses slip right through. Whether or not this is important depends on your water source. If it receives large amounts of untreated human waste, whether directly or from tributary streams, the threat of viral disease looms large. Conventional wisdom — and much official advice — suggests that waterborne viruses are most often encountered in densely settled regions, particularly in the world's tropical latitudes. But conventional wisdom many not be a very useful guide in our fast‑changing world, particularly when budget constraints now force many rural communities in Canoe Country to think twice before upgrading (or even maintaining) their sewage treatment plants. This year's spring floods in North America have taken a lot of small‑town treatment plants offline for periods ranging from days to weeks. It's anyone's guess when they'll all be back up and running at full capacity. Yet the toilets keep on flushing.
And then there's the rural counterpart of urban sprawl to consider. As growing numbers of folks build vacation or retirement homes in remote areas, more and more wilderness waterways are subject to runoff from inadequate or improperly sited leech fields. I've no idea of the magnitude of the problem. I doubt if anyone does. But I do know that early‑season paddlers on many formerly pristine rivers can now follow their noses to identify multiple possible sources of fecal contamination. These are anecdotal reports, to be sure, but I think it's always best to trust the evidence of your senses, even if it hasn't yet been reflected in official sources.
That being the case, what's a worried (or cautious) paddler to do? Well, the only certain rule was articulated long ago by the peripatetic writer Colin Fletcher: If in doubt, doubt. Then treat the doubtful water. But just how should you go about it? That's the question, isn't it? And here's …
I've relied on a two‑step approach for some years now. I bulk‑treat water with a microfilter in camp to remove bacteria, protozoan pathogens (Giardia and Cryptosporidium, mostly), and the infective stages of the Echinococcus tapeworms. After that, I hit the filtered water with a low dose of tetraglycine hydroperiodide (equivalent to 1 ppm of free iodine, more or less) to knock out any viruses. At least that's what I did. I don't do it anymore. Don't get me wrong. It worked. Once I adopted this two‑step approach, I didn't suffer any illness I could attribute to contaminated water. But then fallout from the Cold War caught up with me — literally, as it happens. I fell victim to atomic‑testing‑related thyroid disease. The upshot? Tetraglycine hydroperiodide was off my menu. Permanently.
What next, I wondered? I could keep my filter, but I needed something more to take out any viruses. I began by rereading my earlier articles on water treatment for Paddling.net. (I had to start somewhere, right? And it had been a long time.) One of them contained a couple of paragraphs about an early incarnation of the SteriPEN, a clever device that relies on ultraviolet radiation to inactivate waterborne pathogens. My initial take on the SteriPEN wasn't particularly encouraging, I'm afraid. In fact, you could say I damned it with faint praise. But rereading my old column encouraged me to give the little lightsaber — that's the tag I gave the SteriPEN in the original article — a closer look. I liked what I saw. So I bought one: a SteriPEN Classic, to be exact. It was much cheaper than when I first wrote about it, too. That helped clinch the deal. I also bought the prefilter.
Now, three years on, I'm happy to say that the dismissive comments in my old article were altogether unwarranted. My SteriPEN has proven simple to operate (you can download any of the SteriPEN User's Guides here), reliable, and — insofar as I can judge, at any rate — effective. At least I haven't come down with any waterborne ailments. I find some operational constraints frustrating, however. Since the SteriPEN can treat just a single liter at a time, this creates a bit of a bottleneck. Still, each treatment cycle takes only a couple of minutes. It's not a crippling handicap. In fact, there's good reason to treat bulk‑filtered water with the SteriPEN only as needed. UV light doesn't kill infectious microorganisms outright; it simply prevents them from reproducing. But prolonged exposure to natural light can actually reverse the inhibitory effects of earlier UV exposure, a phenomenon known as "photoreactivation." That being the case, it makes sense to treat only a quart of water at a time with the SteriPEN, and then keep the bottle of treated water out of the sun except when drinking. (An opaque water bottle would do the trick, too.)
Battery consumption also remains a concern, but since many of my trips are relatively short, I mostly use rechargeable NiMH cells, with a couple of sets of lithium cells as backup. And speaking of backup… Good as the SteriPEN is, I don't trust any electronic gadget completely, particularly when the gadget in question incorporates a fragile glass tube, as the SteriPEN does. So I carry chlorine dioxide tabs in my pack in case the SteriPEN's little green light ever fails to wink reassuringly.
OK. That's the overview. But what's the …
The Bottom Line?
No surprises here. I like the SteriPEN. In fact, I like it so much, I'd be tempted to make it my primary treatment device and leave my filter at home. But there's a worm in the apple, so to speak: the Echinococcus tapeworm. Echinococcosis (aka "hydatid disease") is no joke, and you get it by ingesting the tapeworm's infective stages ("embryonated eggs") in contaminated water. While conventional wisdom — here we go again! — suggests it's a danger only in some well‑defined areas (Isle Royale National Park is one), I'm uncomfortably aware that the causative organisms are widely distributed throughout both hemispheres. Moreover, dogs are the definitive hosts. Either Fido or Lobo will do; the tapeworm doesn't care. It's happy to hitch a ride in foxes and cats, too. Given all this, it's hard to see how any Canoe Country waterway can be assumed to be entirely free of risk. And now for one final piece of bad news: There's no reason to believe that the SteriPEN is effective against the infective stage of any Echinococcus species. In fact, there's good reason to believe it isn't.
The upshot? I won't be retiring my filter. (Happily, tapeworm eggs are much too big to pass through the pores of a microfilter.) But I will continue to use my SteriPEN to insure that no viruses escape to do me any mischief — a lightsaber is now my constant companion in the backcountry. You'd have to pry it out of my hands to get me to give it up.
So much for first impressions, eh?