Backcountry Water Treatment Part 4: Methods for Making Water Safe

This thread is for comments on the article "Backcountry Water Treatment Part 4: Methods for Making Water Safe"

All drinking and cooking water should be treated, regardless of how clear and clean it looks. (photo: A. MacLeay) Short o...

Full article at http://www.trailspace.com/articles/backcountry-water-treatment-part-4-methods-for-making-water-safe.html

I work for Katadyn as their northern rockies representative. I have done a lot of research into what is in backcountry water and how to make it safe.

Unfortunately there are a few major errors in your water articles and a lot of information that is either left out or glossed over.

I will address the errors.

1. Iodine does not kill Cryptosporidum. Cryptosporidium is a protozoa that first hit the news in 1993 when over 400,000 people in Milwaukee caught it. Symptoms are similar to Giardia and it is just as common. It had simply not been researched much until the Milwaukee outbreak made the news. A 1992 study of U.S. rivers and lakes fouund 97% contained Giardia, Cryptosporidium, or both.

2. Boiling time. Both the Environmental Protective Agency (EPA) and the Center for Disease Control (CDC) recommend boiling water for one minute unless you are above 6,700 Ft., then the recommend goes to three minutes. I'll take their advice-but boiling water for all your needs in the backcountry is a real pain.

3. There are now more popular and easy to use forms of Chlorine on the market than noted in the article. Tablets that produce Chlorine Dioxide are marketed under 3 brand names. Micropur (Katadyn), Potable Aqua Chlorine Dioxide, and Aqua Mira Chlorine Dioxide. They will kill all micro-organisms in any kind of water, but take 4 hours to kill Crytosporidium in cold dirty water.

In Asia and South America, where killer viruses can be present I microfilter first to remove hard to kill protozoa (and also bacteria and turbidity), then I add Micropur tablets. EPA required testing indicates that Micropur will kill all virus within 15 minutes. I just returned from a 16 day Nepal trek where we used this technique and everyone's intestines stayed happy.

My recomendations for North America are a good quality pump microfilter, with Chlorine Dioxide tablets for backup. In 20 years of using pump filters on many, many multiday trips I've only ever been mad at one. I've never seen one irrepairably clog, break, or otherwise fail.

Thanks, Riverridgeray.

Welcome to Trailspace, Riverridgeray, and thanks for the feedback.

I've edited the article to reflect your suggestions and clarifications.

You're right that we had an error of omission and should have stated that idodine doesn't kill crypto. I also expanded our mention of the chlorine dioxide products available, as well as the CDC and EPA's boiling recommendations.

Hopefully I've addressed all issues of confusion. Thanks again

Alicia: Thank you for so quickly making those changes in the article. I realize I did not leave a comment in the "What's in backcountry water comments" but I think more information on Cryptosporidium is needed there. Two years ago I put my college science degree to work, did a bunch of research, and knocked out a 12 page, hopelessly technical paper on "What's in the Water Now." I will email it to editor@trailspace.com for your perusal and or use.

http://ezinearticles.com/?Whats-in-the-Water-Now?&id=710636

Here is a link to the article on line. It got butchered a little in the posting, since they couldn't handle footnotes. thanks, riverridgeray

Riverridgeray -
I had not responded before now because I was out in the backcountry in snow for a week, then only had access to the web away from my reference materials. Since I returned home, I have cross-checked my article with several professionals in the field (we here in the SFBay area are blessed with having a number of active wilderness medicine research people, including authors of the several of what are considered to be the authoritative compendiums on the subject). Although I have training and certification in wilderness medicine, I am not myself an MD (my doctorate is in another field). I will be posting a detailed response, hopefully this week, with references to the literature.

Briefly, though, keep in mind (as posted earlier in the discussion of one of the other segments), the article was not intended as an exhaustive scholarly review of the field, but rather as a brief summary of the salient points of practical use for the backpacker and climber. It was not intended to cover all possible environments and disaster scenarios, but rather the wilderness situations encountered by most of the readers of Trailspace. There are some omissions and oversimplifications that were made in the interests of conserving space (originally, the intent was a single article, but Alicia wisely split it into 4 more readily readable sections). I will be doing a bit of editing to clarify several points.

I will note that, according to 2 of my acquaintances who are recognized wilderness medicine experts, there are several misleading or erroneous items in your post, and in the "ezine" article you link to. Without going into detail at this point, here are a couple -

1. While it is true that giardia and crypto are resistant to halogens (both chlorine and iodine), especially in the oocyst form, it is not true that "iodine does not kill" crypto. As I noted, the effectiveness is dependent on temperature and turbidity. Given sufficient time and temperatures of 20-30C, crypto cysts are killed (65 to 80% inactivation after 3 hours, 3log inactivation after an additional 4 hours with 2 iodine tablets in "general case" water). Note that the Milwaukee incident involved a failure of the municipal filtration system, and in a city using chlorine dioxide, not a wilderness situation.

2. The boil time recommendations from EPA and CDC are for sterilization of the water, not purification, and are primarily driven by the lack of data for Hep A. Sterilization means killing all the organisms. There are bacterial cysts that do not cause problems in humans that can withstand boiling water, but most biota that cause harm are inactivated at pasteurization temperatures of 155F (including giardia and crypto, as well as most viruses). In fact, as an emergency measure, it has been noted that international travellers can significantly lower their risk by using the hot water (as hot as your hand can stand) from the tap of hotel sinks (most hotels in foreign countries do not have the 120F limitation on hot water that we do in the US - this is lower, not eliminate). One clarification I will add is this - since most people do not carry a thermometer into the back country to determine the water temperature, to be safe, raise the water to a boil. This is not when bubbles start forming in the water on the bottom and sides of the pot, but when a full rolling boil starts.

I will be giving the references later. But for a quick reference in a single compendium, you can refer to Paul Auerbach's book Wilderness Medicine (the 5th edition has come out recently with updated information). The book itself is huge enough that you need the DVD-rom that goes with it to readily search the references.

I have noticed that when discussing giardia & cryptosporidium some product literature uses the term "kill" and some use the term "inactivate".

I have also read that iodine does not "kill" crypto, however it seems to me if all you need to do is "inactivate" giardia & crypto so it can not reproduce and make you sick then the iodine would be effective against crypto.

It has in the past seemed to me that this is purely a game of semantics between competing brands of chemical water treatments.

Or am I all wet?

trout,
You are correct that there is a lot of semantic gaming involved. There are technical meanings to "disinfection", "purification", "potable", "inactivate", and "sterilization" that are not necessarily obvious to the non-technically educated consumer. For example, "potable" means "drinkable" with a statistical likelihood of illness that is "acceptable" (if I am the one who gets super-sick and have to be evacuated, it ain't acceptable, but if I'm the only one in a million, that's considered more than ok).

"Kill" means it is dead and the organism will cause no problems (some bacteria and other organisms generate waste products while alive that are not destroyed and will continue to make you very sick, salmonella being an example). Iodine will in fact kill crypto, given sufficient exposure time at a high enough concentration at the right pH, though the time required is fairly inconvenient. "Inactivate" means the organism goes dormant and will cause no problem for a while - bacterial cysts being an example - but will eventually become active again.

As for inactivate, UV (Steripen, for example) does kill most biota, but inactivates others for long enough to drink or use in food preparation safely, but does not have a lingering effect (as do halogens), so some of the critters can stir themselves back to dangerous levels if the water is left in the water bottle long enough.

There is a list, which I should reproduce here, of "claims" terminology that the CDC and EPA have placed requirements on and "claims" terminology that has no accepted meaning in a book I recently acquired on disaster survival.

I should note that the filter I use most, the Katadyn Hiker Pro, is intended for high-quality surface water in the US backpacking market. It is recommended by Katadyn (coincidentally riverridgeray's company) that halogen disinfectants be used for international travel or where high levels of contamination are possible, which includes events such as the recent Midwest flooding, Hurricane Katrina, or our occasional West Coast large earthquakes, where there may be a large increase in the content of viruses. From reviews like Backpacker publishes, you can get the impression that such filters are good anywhere, anytime, under any level of contamination.

I note that riverridgeray says that in 20 years, he has neveer seen a filter

irrepairably clog, break, or otherwise fail

Well, sorry, but I have seen failures with every brand of pump filter over the last 25-30 years. Maybe "irrepairably clog" does not include where you have a spare element to swap out, but I have seen every brand clog to where the filter element could not be cleaned by brushing or backflushing, notably in areas like Philmont Scout Reservation, where they run a couple thousand youth through per week during the 12 week summer season (my son was a Ranger there and reported the same thing to me). I have seen filter elements (especially ceramic) cracked by freezing when people neglected to make sure there was no water remaining when the temperature was dropping well below freezing, and seen them cracked in careless handling. Plus I have seen many broken pump handles, hoses getting so worn they would not stay on the hose bib (the push-on inlet or outlet), etc. Most of these failures were user errors and/or ignorance, but some were due to age or water laden with glacial flour or volcanic ash.

Note that my personal choices are boiling for water that I am cooking with (have to heat it anyway), Steripen for water that is sufficiently clear, filter with settling and prefiltering if there is turbidity, and halogens for quick and dirty desperation backup (iodine if I want the water fairly quickly, chlorine dioxide if I can wait the 4 hours). I haven't had a water-borne sick spell in several decades (actually none ever that I know of, though I got really sick from a shrimp cocktail served in First Class on an airline, along with all 5 of my travelling companions). But then, given the claim in riverridgeray's "ezine" article of most long-time hardy outdoors types being carriers, maybe I am just "Giardia Bill" or "Crypto Joe".

Bottom line - treat all your water by one or more means, and make sure your hands are clean either by soap and water or Purell before handling food or putting your hands near your mouth.

I have been using filters, followed by chemical treatment for about 20 yrs.
I also pay close attention to personal hygiene as well.

I currently use the Katadyn Hiker Pro with Micropur & the MSR Sweetwater Purification System with Viral Stop.

I like both systems, but anything with moving parts can and will fail under the right circumstances, and almost always when it is being used.
At least that has been my experience.

I should add that, if I know the water is really really contaminated, I use the Pur kit that is described at the end of the 4th installment. Since that works on 3rd World mudhole water, that should do it. Problem is, I am running very low on the chemical packets, so I am storing the remaining ones for a major natural disaster (or if I somehow get transported to Zimbabwe or Somalia). Alicia and I have had a lot of difficulty in dealing with the Pur distributor, and I don't know of a local source, other than the on-line ordering site. It would sure be great if somehow a large number of the kits could get shipped to those unfortunate countries, where the people are resorting to drinking water containing raw sewage.

Bill S. It appears the two parts of my posts that bothered you the most were.

1. My assertion that Iodine does not kill Cryptosporidium. I confess I could have stated that a little more lawyer-like. Let me try again.

Iodine does not kill Cryptosporidium when used according to manufacturer’s recommendations in any reasonable amount of time. Let me quote my source.
From: Wilderness and Environmental Medicine: Vol. 8, No. 2, pp. 96–100.
Efficacy of iodine water purification tablets against Cryptosporidium oocysts and Giardia cysts CHARLES P. GERBA, PhD; DANA C. JOHNSON, PhD; MICHAELA N. HASAN, MS

To sum up the above paper I'll use one quote:
"These data strongly suggest that iodine disinfection is not effective in inactivating Cryptosporidium oocysts in water. Because this organism is common in all surface waters, it is recommended that another method of treatment be used before ingestion”.

2. Boil time. I'll stay with "sterilization" and the recommendations of the CDC and EPA over other assertions. 1 minute up to 6,700 Ft. and 3 minutes above seems easy to achieve in most all situations.

Although I do more than my share of solo wilderness trips, maybe of my trips are multiday whitewater float trips. We commonly pump many gallons of water per day. When you have group of people on a multi-day river trip: those pumps get a workout.

I do see and hear about broken and clogged pumps from Katadyn and other brands. I will stick with my assertion that I have never been on a trip where the pump filter completely failed from clogging or breakage. I've done a lot of cleanning of prefilters and filters, lubrication of gaskets, and I do try to avoid really dirty water. But I've even pumped for 16 people on a 18 day Grand Canyon float without totally trashing my filters.

thanks for your interest! riverridgeray.

Bear with me. I wrote the above post in Word and then cut and pasted it in. There was some movement of words when it uploaded. Since health information is important. I will repeat the parts that are messed up.

Bill S. It appears the two parts of my posts that bothered you the most were.

1. My assertion that Iodine does not kill Cryptosporidium. I confess I could have stated that a little more lawyer-like. Let me try again. Iodine does not kill Cryptosporidium when used according to manufacturer’s recommendations in any reasonable amount of time.

Let me quote my source.

From: Wilderness and Environmental Medicine: Vol. 8, No. 2, pp. 96–100. Efficacy of iodine water purification tablets against Cryptosporidium oocysts and Giardia cysts

CHARLES P. GERBA, PhD; DANA C. JOHNSON, PhD; MICHAELA N. HASAN, MS

To sum up the paper:

"These data strongly suggest that iodine disinfection is not effective in inactivating Cryptosporidium oocysts in water. Because this organism is common in all surface waters, it is recommended that another method of treatment be used before ingestion”.

riverridgeray,

It serves no one to get into a p-ing contest. But some of your statements are a bit misleading. When you state flatly that iodine "does not kill" crypto, you are not correct. It is correct to say that crypto, especially in the oocyst form is highly resistant to iodine (and chlorine, for that matter). It is also correct to note that halogens are much less active at low temperatures (which are commonly encountered in mountain streams, the environment we are talking about) and if the pH departs significantly from 7.0. It is also correct to state that most backcountry travelers do not have the patience (and may be unaware) of the time required or of the time/temperature effect. This is no doubt what you are referring to in your comment about "any reasonable amount of time." It is not correct to state flatly, as you did, that iodine does not kill crypto. If you make that statement, you also have to state that chlorine, including in the form of chlorine dioxide, does not kill giardia (times of 4 hours and longer are not really very reasonable, with 8 to 12 hours being required for giardia cysts with water at the 35-40°F found in many mountain streams much of the year).

Since filters of 1 micron pore size (not just "effective pore size", but actual pore size) and smaller are effective at removing protozoa (like giardia and crypto) and many of the problem-causing bacteria, filters are a good first step. However, filters are ineffective against many viruses which are present in water in major rivers and lakes in the US and in most water sources in Third World countries, as well as disaster-disrupted water supplies anywhere. Halogens applied after filtration are effective against the majority of these viruses (the hepatitus and HIV groups are notable among these). Passing filtered water through an iodine resin matrix (which several of your company's filters used to have in the series purchased from Pur, and your bottle/straw still has) has been found to be effective for these viruses.

Your statements on boiling are the result of confusion of terminology. The medical and public health community designate several stages in reducing the effectiveness of contaminants in water. "Potable" means that the water is "drinkable" and that there is "minimal microbial hazard" so that the statistical likelihood of illness is acceptable. "Disinfection" is a process that kills or destroys nearly all disease-producing microorganisms except bacterial spores (some of which can survive for long periods in boiling water at 100°C/212°F). Basically, this is the goal for wilderness water treatment. "Purification" means the removal of organic or inorganic chemicals and particulate matter to improve taste, color, and odor. Note that the term "purification" is often used when "disinfection" is meant (including in my posts). "Sterilization" means that all microbial life, including bacteria, viruses, protozoa and spores are destroyed. At this stage, the water can be used for surgical purposes. The CDC and EPA recommendations for boiling times are intended to produce water sufficiently sterile for surgery and other medical procedures, with this specifically being to destroy hepatitis A . If the disinfected level reached at 155°F/70°C is not sufficient for you, then you should avoid pasteurized products like most commercially sold milk in the US (a number of European countries have sterile milk standardly in their stores). Protozoa like giardia and cryptosporidium are particularly vulnerable to temperatures of 140°F/60°C and higher. Look at Auerbach, Wilderness Medicine, 5th edition, p 1377 and the references listed there for a detailed discussion.

One note to be added in my revision of the articles will note that while streams in the Rocky Mountain, Cascade, and Sierra backcountry show an absence of giardia and cryptosporidium or a number of cysts per liter well below the level considered to pose a risk in the vast majority of samples, there are occasional spikes that do pose a significant risk, probably due to seasonal runoff, sporadic animal activity, and/or presence of humans who fail to practice basic sanitation. Therefore, at the minimum, it does not hurt to treat the water to be drunk (like wearing your seatbelt in the car or wearing your helmet on bike or skis, you may go for years with nothing happening).

Note well that I have not said anything remotely resembling "it's all safe, don't bother with treating the water." Instead, I am saying practice basic sanitation, since all the evidence shows that by far the major source of backcountry illness is failure to wash or disinfect your hands or your food handler's hands, while at the same time taking basic precautions with the water you use for drinking and with your meals. Prevention is far better than the cure, and the cure may be days away from where the problem arises.

Yeah, what Bill said.

I used to own and use the PUR purifier with a prefilter, charcoal top, and filter with a iodine resin matrix. It was a great filter I thought.

There does not seem to be a backpackers filter on the market like that now, were there liability issues with claims made or what's the deal with that? Or am I overlooking a product?

Currently I both filter, and treat chemically, just 'cause I want to play it safe. Being real sick on a solo trip is no fun, not to mention that you can get sick days after a trip as well.

I take soap & Purell or equivalent, I don't see the reason to filter or boil water when you have contaminated all your gear (like your filter hoses, water bottles, cup, etc.) with nasty hands.

And yeah, they are nasty after a couple days with no washing.

Bill, riverridgeray--

Seems to me that both of you are knowledgeable and have lots of good information to share. As an MD, and having read the articles involved, the comments, etc., I'll go so far as to say that you have both in general taken reasonable, responsible opinions. The type of disagreement arising here is a not uncommon one in the medical and scientific fields. In a Journal Club discussion of even a highly reputable article, the fur may fly with abandon at times. So, in the interest of harmony, world peace, and reduction of carbon dioxide emissions, may I suggest that you both take a deep breath, count to ten, and then respond as if your mother were watching?

I'm not intending to be paternalistic or whatnot, just hoping to help keep the peace between what I perceive as two well-meaning individuals. If I've offended one or both of you, I apologize.

Just to give you both opportunity to redirect yor fire, however, consider this: Giardia is not nearly the risk that it is generally made out to be, nor is cryptosporidium, for most folks. Absolute safety whilst ingesting water in any locale is impossible. Therefore, the reasonable person will seek to make the risks "reasonable" to him. As far as I can tell, the approaches you both advocate are reasonable. I don't routinely follow either one. (So there, hah!)

Note to anyone reading--this does not constitute medical advice regarding water ingestion, potability, purification, sterilization, or any of those things. If you wish to obtain medical advice appropriate to your health and circumstances, see your personal health care provider.

Perry Clark said:

...
consider this: Giardia is not nearly the risk that it is generally made out to be, nor is cryptosporidium, for most folks. Absolute safety whilst ingesting water in any locale is impossible. Therefore, the reasonable person will seek to make the risks "reasonable" to him. As far as I can tell, the approaches you both advocate are reasonable....

Well, Perry, I do not advocate any particular approach for water treatment (although I do advocate being sanitary when it comes to personal hygiene and especially for the food preparers). The point of my articles was to present the information that is out there, as it relates to North American backpacking areas, so that people would know the alternatives and could choose for themselves. I have no system to promote (unlike ridgeriver, who is a Katadyn representative). I listed some (but not all) the advantages and disadvantages of each approach (boil, chemical, UV, coagulation/flocculation). My problem with ridgeriver's posts is with his dogmatic statements that disagree with the wilderness medicine community's research (I relied on several of the people who seem to be considered the leading experts for reviewing what I wrote).

I completely agree with your statements that the risks of giardia and crypto are overblown for most people in most of the backcountry in the US, and that complete safety is impossible. Some people have other health issues and should take extensive precautions, of course. And, as I said, it doesn't matter if the odds are 0.0000001 of getting one of the waterborne diseases if I am that one person. If I am not comfortable with those odds, then I should take extra precautions - belt and suspenders, so to speak. Since no one system takes care of all the risks (viruses get through filters, crypto is resistant to halogens especially for the cold water coming from streams, UV does not have a ligering effect, some bacterial spores will survive boiling water...) as I stated, it is reasonable to take a multiprocess apprach, if that makes me more comfortable (still keeping in mind that this is still not perfect).

Hopefully, having the information that is out there in the wilderness medicine community will allow people to make a more or less rational choice without succumbing to the scary ads of the companies selling products.

I suspect there is a lot of truth to the statement that a number of long-time backcountry travellers may have resistance or some level of immunity to many of the waterborne illnesses (and may be carriers, in turn). I have had the experience of being on climbing expeditions where 2 or 3 of the party got very sick, while the rest of us suffered nothing at all, despite eating the same food and sleeping in the same tent. Maybe part of that in my case came from growing up in fairly primitive conditions in the Arizona desert, coupled with living for a while at a very young age in Central America and our family travelling a lot in Mexico. I see these articles claiming that one reason so many children have allergies these days is that they are so protected from exposure to "germs" that their immune systems do not develop as well (I also suspect this is one of those areas you referred to with your comment on vigorous debate, even on well-refereed articles in professional journals).

Bill--

Thanks for the reply. I think you're spot on with both your approach and description of methods, options, etc. And I'll certainly acknowledge that riverridgeray might have a different dog in the fight. I just kinda wanted to remind all that making decisions about water filtration/treatment, etc. isn't something wherein there's always only one "right answer". And I'd certainly echo your comment that it's almost always more important to practice good, clean food preparation techniques and proper personal hygiene.

 

Thanks, btw, for preparing the article series. Quite good, I thought, and I'll be referring folks to it for their own edification.

 

BTW, you're right about the childhood allergy thing being one of those topics that can get people riled up. And we won't even talk about immunizations! Whew!