Water purification in extreme conditions

11:58 a.m. on October 19, 2007 (EDT)
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And I do mean extreme! I am asking for some input here from people who have had experience dealing with the problems to be described. (WHAT!!! The OGBO is asking for information????)

As most here know, I have dealt with a wide range of conditions from desert to Arctic/Antarctic. I have used (successfully, since I have never gotten any water-borne illnesses when in the woods and hills) a number of approaches (filters, chemicals, boiling, UV, and even - gasp! - purchasing commercially bottled water). I know to avoid situations like we have in my local hills where there are abandoned mercury mines that produce chemical runoff into the streams and reservoirs (yes, Almaden Valley, just a hop and skip from Silicon Valley, no jump needed, just go for a hike in Almaden-Quicksilver County Park).

The situation is this - we are headed for Africa for a photo-safari. We will be camping out for a couple weeks, and at least some of the water sources will be shared with critters like elephants, lions, etc, who stir up lots of mud and don't bother with LNT practices like disposing of their organic waste 200 feet from the water.

I have been trying various experiments like making muddy water by mixing sandy and clay dirt into water and trying various methods to remove enough of the material before treating. A Steripen, for example, requires clear water to work, and filters clog quickly. In my experiments, I have tried prefiltering with coffee filters and pre-filters from the filter manufacturers, as well as filter bags from a chemical supply house (supposed to remove stuff down to less than a micron), plus letting the water stand overnight to settle the sediment and decant. All of these leave cloudy water with some coloration, too cloudy for a Steripen, and murky enough to clog a pump filter after just a few gallons. Basically, none of the prefilters work to a sufficient level.

So, the problem is - how does one clarify the water sufficiently to have a multiweek use of a pump filter (hopefully reducing the daily scrubbing of the cleanable filters to a weekly or less level) and/or to let a Steripen work? Yes, boiling makes the water sterile, but there is this murky junk to drink - safe enough, but not aesthetically appealing. Chemical treatment (iodine or chlorine based) is effective, but again leaves the water murky.

Remember, this is an advanced question, not your basic, "how can I get pure water in the Sierra, Rockies, or Presidentials" question. Techniques that have worked for me on glacial till and volcanic ash don't seem to be working here.

8:54 p.m. on October 19, 2007 (EDT)
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That's what I fear is the answer. However, after posting, I did recall that there is one solution for in the field, namely the PUR treatment that either is about to come out or just did (can't recall, and need to look it up). The problem with it is mostly that you have to treat in batches of 2.5 gallons at a time. This might be acceptable during the time we are moving from place to place in a Land Rover, but not during the hiking phases of the trek. Plus, I think it will be (or is) pretty costly.

Dave, you may have more information of the PUR approach.

So I am still looking for solutions. I should have noted that murky water also requires longer times for the chemical (iodine or chlorine) approaches, and may require increased doses of the chemicals. So the turbid water affects all the "standard" methods.

I really really do not want to interrupt the expedition to spend time dealing with intestinal disorders.

9:20 p.m. on October 19, 2007 (EDT)
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Hi Bill,

The PUR Purifier of Water treatment could be a solution.

Each 4 g (0.14 oz) packet treats 2.5 gallons/10 liters and takes 30 minutes.

Step 1. Mix: You add the packet (0.542% calcium hypochlorite, 99.458 % other ingredients) to 10 liters of water.

Step 2. Stir: Stir well for 5 minutes. Let stand for 5 minutes. If water is not clear stir again until the floc is separated.

Step 3. Filter: Use clean thick 100% thick cotton cloth without any holes to filter. Dispose of filtered floc away from children and animals.

Wait 20 minutes.

Step 4. Drink

It'll be sold two ways:

1. as six (4 g) PUR packets and a cotton filter cloth ($14.99)

2. as a kit with mixing container, storage container, stirring wand, cotton filter cloth, packet opener, and three Pur packet ($28.99).

My press info says the product is new for 2008, but expected sometime late 2007. I'll check into that more and report back. As you already know, it's been used internationally for several years, specifically for natural disasters and emergency situations.

The web site is: http://www.purpurifierofwater.com/
but so far has no actual info on it.

9:50 a.m. on October 22, 2007 (EDT)
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I would vote for Ed's idea for a preliminary filter. That said, there has to be some sort of process to do exactly what you are attempting to do. Have you checked any sort of disaster relief sites such as the Red Cross or other international agencies? Somehow these folks have to know how to treat nasty looking water. Bring lots of medicine just in case the treatment process doesn't work. Keep us posted as to what you come up with as it's good information to know.

1:54 p.m. on October 22, 2007 (EDT)
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Hujambo, Alan (I'm trying to learn some Swahili, but that's most of my current vocabulary) -

Red Cross and other international agencies are using reverse osmosis systems that are too bulky for our trip, and the system that Alicia mentioned. That PuR system was developed by PuR in conjunction with Proctor and Gamble as a way of getting inexpensive purified water on a small scale for organizations like UN agencies, Red Cross, etc. We are looking into whether it is available to private individuals at this point (the literature that Dave and Alicia and I picked up at the OR Show seemed to indicate that it won't be available for individuals for a few more months).

The other approach used has been to let the water settle for a while, decant the clearer stuff, then boil the water. I have done that sort of thing when canoeing or kayaking on the lower Colorado River, but it leaves pretty murky-looking water (never got sick from it, though).

The prefilter is good, to a point. I think the Sweetwater pre-filter (which I have, with several refills) may be ok to put on one of my pump filters to keep them from clogging. But I have found (as previously noted) that coffee filters and the standard bandana or "clean cotton cloth" just take out the big stuff. Even a commercial filter bag (0.5 micron) made by a company a friend works for leaves my test mixture output looking too murky for a Steripen, and it leaves it requiring at least a double treatment from Miox (part of the Miox kit is indicator paper that should turn purple after treatment is complete).

Reverse osmosis is also a way of desalinating water, so units are available for sailboats and much used by the ocean racers, even for those crazy folks who sail solo in the Drake Passage. But the smallest of them in my neighborhood West Marine are much too bulky for even checked baggage on the plane.

I won't have a problem when up on the mountain, since the mountain streams are pretty clear. It's just when out on the Serengeti and similar places where we have a few days where we have to share the waterholes with the "Big Five" and their smaller cousins.

By the way, as I have been reviewing treatment methods, I was reminded that, while iodine requires a half hour (relatively clear water at 20C or above), chlorine dioxide, the big current favorite among backpackers, requires 4 hours away from sunlight(!) to fully react (again, relatively clear water, 20C or above).

The backpacker-type pumps will work. It's just the clogging problem. The backpacker pumps with a carbon final element (the Katadyn filter bottle, for example, or the Sweetwater, or any pump with the Katadyn carbon post-filter) will remove some heavy metals and some organics (which means pesticides or fertilizers), but the manufacturers won't give any numbers on how effective they are for this, unlike their numbers for the tiny critters.

5:09 p.m. on October 22, 2007 (EDT)
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An idea for inventors: a portable "still" to distill "pure" water vapor from bush sources, which might include a 1-5 gallon input reservoir, a vaporization chamber, a cooling/concentration coil and a 1-10 gallon fresh water storage reservoir. The only thing missing are efficient heating and cooling sources. Perhaps auto (or boat) engine or exhaust for heat and an auto or portable air conditioner (or other refrigeration unit) for cooling. Fresh water could be distilled while on the "road," enroute to camp or while siteseeing. With a little time, I am sure even a jury-rigged (gerry-rigged?) device could be fabricated before someone fine-tunes the idea. Of course, filters and clean-outs will still be necessary--the residue has to go somewhere. I don't think I'd want to pack it on my back, but I could envision having the Land-Rover do most of the heavy work.

7:00 p.m. on October 22, 2007 (EDT)
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Reverse osmosis would require significant pre-filtering to work. The membranes would clog very quickly otherwise. This may not be apparent in the systems you have seen, but there are prefilters.

I am not aware of any pump type filters that would not require daily maintenance on your part or that would not require several spares just in case. The pleated type (Hiker) would go longer before maintenance is required, but the type of water you describe would fill them up rather quickly. You could rinse them out a couple of times, but then you'd have to replace. Ceramic type filters (Miniworks, Pocket Filter) would require a lot of maintenance, perhaps every liter or two for the really murky stuff. Prefiltering would help, but the prefilter would have to remove really small stuff to make a real difference. Settling/decanting might be your best bet unless you can come up with some sort of a still setup.

So I guess there are no real good alternatives that I can think of that will give you clear water. You're trying to treat the type of water we normally try to avoid for this very reason. Any way you slice it, if you want aesthetically pleasing water you're going to have to work for it. And there's no way around thoroughly treating water there if you don't want any intestinal visitors.

Personally, I would opt for settle/decant, and then filter with either a Hiker or a Pocket Filter (the latter being, in my experience, the least likely of any filter I have seen to cross contaminate when cleaned using proper technique).

One last thing to consider is that a filter with carbon will greatly improve the taste of the water. I would guess that you will be taking water from sources that could be rather foul.

I assume you are using some sort of a guide service. Do they have any large drip or gravity filters?

12:18 p.m. on October 23, 2007 (EDT)
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I'd contact folks at Safari Club International or perhaps the Texas Safari Club - get the names of some outfitters / guides / professional hunters in the area(s) of Africa you're planning to go, then contact them to see what in-field solutions they use to purify water for their hunting clients. Some of these safari's are on foot with little or no outside support - and I can't see some "master of the universe" heading out to kill the "big five" of dangerous game putting up with getting a case of travelers trots -

The CDC may have some interesting information also.

From what I've read (never having gone, yet) there are some interesting water based creatures, both micro and macroscopic that can play havoc on the human body if ingested or (in some cases) absorbed through your skin - most are regional - so info from the locals would seem to be appropriate.

6:10 p.m. on October 23, 2007 (EDT)
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Chumango -
Tanzania (and most of the African countries) has a requirement about hiring local guides, porters, and such ... unless you are with one of their rangers. The guide services mostly use hotels (and some fancy "camps" that put KOA to shame). We get the more primitive approach of traveling with a ranger acquaintance (but get to get more up close and personal). After Barb returns to the US, I am hiking up Kili, and there I can use mountain streams that are clear (albeit being habitat for some nasty critters, thanks to some of the latrines being very close to the streams, like within 20 meters or less). For the mountain, the Steripen and a regular pump filter are just fine. It's just in the game parks where we will be away from clean sources for a few days.

The PuR approach appears to be promising, with the possibility of introducing the technology to some of the villages (that's why P&G and PuR developed it, though they haven't got much presence in Tanzania at this point). If we do get things arranged for this, the 10 liter unit size is not a problem, as it would be for parties of less than 5 or so. It's not clear whether I can qualify for a pre-retail package, although they are interested in the arrangements for our trek.

A couple of people have mentioned stills - there is an energy consumption problem. The cost is more than the PuR chemical flocculation approach - note as mentioned in Alicia's post above that 6 packets is $15 (treats 60 liters or about 15 gallons of water that can be pretty murky, which is $0.25/liter, a lot less than commercially bottled water. A large bulk purchase can get it down to under 10 cents/liter. The other packaging she mentions includes the mixing and storage containers and stirring paddle.

Fred, thankfully, we will not be going into any of the areas where the little "worms" that can enter through unbroken skin reside. But, again, the approach the big game hunters use (aside from staying in hotels that have sizeable treatment facilities) is a combination of carting along large supplies of pretreated water and boiling. They have a bigger budget than we do (after all, the licenses themselves cost more per person than our entire budget including airfare).

6:52 p.m. on October 23, 2007 (EDT)
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Bill, I have seen a couple of solar stills online. They usually are cone shaped, but one company had some that are shaped like an A frame tent. They look like they are made from plexiglass with a base of black plastic. One I saw had a base about the size of a briefcase.

No idea how effective they are, but if you are traveling by Land Rover or something similar, might be worth considering. From what I see online with one design, they don't put out much water-one only made about 1.5L per day.

12:13 p.m. on October 24, 2007 (EDT)
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Yeah, that's the problem with the solar stills - too little output.

There are lots of approaches, and all have one or another problem. It's almost enough to make one stay in the US in a city with reliable water supplies. Almost, but the "call of the wild" is too strong. If the PuR thing doesn't work out, we will just have to do a lot of boiling and pump filter that gets cleaned a lot (with backup replacement cartridges to go into the filter). Either that or buy cases of bottled water from a reputable supply (except Tanzania does not have a very good plastic recycling program). Looks like there will only be about 3 days where we may have to deal with the mudholes, so it may be workable to use the pump with overnight settling and decanting.

3:56 a.m. on November 17, 2007 (EST)

Water in what was formerly called the "third world" is likely to cause disease and must be purified.

But this topic may perpetuate an unhealthy concern with water quality in North American wilderness that is wildly overblown.

Anyone who disagrees with my contention should first read a very serious and scholarly article published on the Loma Prieta Sierra Club Web site. (search giardia and sierra club for this article on Google).


If you have looked at this, then you are qualified to express a contrary view...I own a filter, and am glad to use it --- but only in certain select locations in North America...

9:23 a.m. on November 17, 2007 (EST)
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Rockwell's paper -- http://lomaprieta.sierraclub.org/pcs/articles/giardia.asp -- deals with one organism (Giardia Lamblia) in one region (the Sierra Nevada). It's a narrow analysis that has little bearing on the topic of this thread: practical solutions for treating water in the African bush.

10:22 a.m. on November 17, 2007 (EST)
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I've poured really murky water through a clean sock into a coffee filter then pumped through a mechanical! This served my needs in the backcountry. Coffee filters are cheap and light and easily disposed of. The sock is reusable.

2:04 p.m. on November 18, 2007 (EST)
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Rockwell's paper, like a lot of stuff in the Loma Prietan (the chapter of the Sierra Club I am a member of) is old stuff. Many of the Loma Prietan articles are often "summarized" poorly from other sources. Tests of water in the Sierra and other parts of the US and Canada have been ongoing for many years by highly qualified researchers and reported in the journals of the Wilderness Medicine Society. Paul Auerbach's small book Medicine for the Outdoors and his much larger book written for physicians give good summaries of the current state of research.

The results have shown some very surprising results (surprising compared to what you would intuitively expect). Some streams and other water sources close to civilization and along heavily used trails within a couple miles of popular trailheads (in many cases, frequented by fishermen) have extremely LOW levels of giardia, crypto, viruses, various bacteria (like salmonella, shigella, e. coli and campylobacter), and other critters that cause problems. Other sources far into the backcountry, including sources at high altitude that are rarely visited by humans, show extremely HIGH concentrations of giardia, crypto, viruses, various bacteria, and other organisms, enough to cause problems from even a cup or two of the water. In other words, apparently safe sources, with water that appears clear to the eye, sometimes test as highly problematic. According to the research, there is no obvious explanation that could be used as a clue to the backcountry traveller. But, again referring to the research published in refereed journals, the overall risk from the backcountry water in most of North America is low, even from front-country water, with the majority of cases of intestinal problems coming from poor sanitation in the preparation of the food (people failing to wash their hands before handling the food). But, since there is no easily spotted clue to the purity of the water, the advice is to always take precautions, such as boiling (actually heating to 158F/70C or hotter, the temperature used for pasteurization of food products, is sufficient, though boiling for 3 minutes even at the lower boiling temperature at 18,000 ft provides a wide margin of safety, according to the WMS sources), chemical treatment, or filtering. (that's like saying the risk of a serious car accident is low for any given trip, but you still should wear your seatbelt for that one drunk driver who might veer into your lane).

As Dave says, though, my original question has to do with water treatment in the African bush, where the water sources are shared with various animals that do not practice LNT. I have also discovered that even bottled soft drinks in the area to which we are headed, do not necessarily guarantee purity.

10:27 a.m. on November 19, 2007 (EST)
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"I have also discovered that even bottled soft drinks in the area to which we are headed, do not necessarily guarantee purity." - nope - it's not. I had a friend get quite ill in Mexico - from bottled water. Yep - it HAD come from a bottle - yee ha. The bottles had apparently been filled from a tap.
I believe you're stuck boiling, filtering or treating your own water when in developing nations, in spite of the inconvenience.
I was very careful south of the border, no ice in drinks (hard or soft), no salads, only ate cooked veggies unless I peeled and prepared them myself and never had a problem. Others in my party weren't so vigilant, nor were some of them as "lucky" as I. I should mention I was there on business and we were staying in a very nice resort hotel complex in a border town, but clean sheets and a clean floor don't mean good water.
Beer, wine and spirits should be safe, if you partake, but as we all know, do nothing for hydration.

9:50 p.m. on December 9, 2007 (EST)
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Hi Bill
Your experience with removing glacial silt can most probabley be compared to the first level cleaning requirement. Coffee filters or cheese cloth first, then filter paper, then mechanical filtering, then chemical treatment. I've had a "cow pond" for a water source and theres really nasty stuff in there. I would imagine that hippo, elephant, wildabeast ponds might be worse. Maybe drive through some mud puddles in your jeep and stir up some good test material, but without the organic component you won't know for sure. Any cow pies in your area to add to the test water?
Jim S

2:11 a.m. on December 10, 2007 (EST)
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Perhaps you should investigate "forward osmosis" systems, which apparently rely on osmotic pressure, and the presence of a "draw solution," rather than pumping as required by "reverse osmosis." Because of this, supposedly, turbidity has no affect on the filter. The US Army Center For Health Promotion Web site seems to imply this is a factual claim for the system.

The only such systems I've heard of weigh only a few pounds, cost several hundred dollars, and are made by Hydration Systems Inc. of Albany, NY.

I don't really understand forward or even reverse osmosis, but there are rather technical entries for both technologies on Wikipedia.

I don't have my copy of Kephart with me, but I recall him quoting an Aussie, faced with a dead kangaroo in the only available spring, who relied on charcoal and settling. I don't recall HW Tilman commenting on this subject in connection with his bicycle trip across central Africa.

As for Dr. Rockwell's work having "little bearing on the topic of this thread," one sees that a number of posts above are much-related to experience in filtering water in North America.

While perhaps, as you say, "many of the Loma Prietan articles are often 'summarized' poorly from other sources," I wouldn't know.

Rockwell's paper, last updated four years ago, does consist of a survey of scientific literature, which is of course a standard and necessary form of scholarly writing. The current version of his paper cites more than 60 sources with very clear footnotes.

Dare I say he makes a bomb-proof case that water purity is an extrememly over-blown concern for hikers in the Sierra Nevada, and by implication, many other areas in the US? I carry my filter but rarely, and am not much interested in the thing.

1:40 a.m. on December 11, 2007 (EST)
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As a missionary, I've heard a lot of debates on water purity in Africa. Here at school we go through training called "Appropriate Technology", or apptech for short. This is how we train nationals in Africa to purify and clean the very water you are talking about. Unfortunately, these methods are long and drawn out, but they do work. The water may not taste very good, but it will be clean. I have used them, and have never gotten sick, even when staying in a wildlife park in Burkina Faso where elephants drank from the same water. All you need are bottles to hold the water, something dark to place them on as you go, sunlight, and filters like coffee filters and/or socks. You have to leave the water on top of the dark thing (whatever you use - we used trashbags) for a few days. I cannot recall the exact amount of time it takes, but I will check and post the actual requirement tomorrow, but it is long. After you've let it get hot for a few days in the sun, put it through the filters. Like I said, it is a drawn out method, and may not be what you're looking for. But, it does work. Others may disagree with me, but I will swear that it works. It just requires patience.

1:44 a.m. on December 11, 2007 (EST)
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Apparently Bill S wants something more "extreme" than your suggestion.

If he seeks merely to avoid illness, chemical treatments would obviously suffice, and there would be no point to his quetion.

3:50 p.m. on December 17, 2007 (EST)

a.k.a. Trreehugger, Scott R

Great topic Bill.
My first thought was to use a pre-filter, then settling & decanting followed by either a filter or your Steripen. As you know, the problem is that really fine clays & organics (ie. those passing through 0.5 micron pre-filters) could take a very long time (days) to settle out. The PUR treatment seems to solve it all by using a combo of a flocculant to clump particles & organisms together yielding clear water & a chemical treatment to kill the remaining bugs. If you can't get your hands on it, you could still use a flocculant to clump up those tiny particles & then decant or pre-filter before using your filter or Steripen. I don't profess to know about the safe or effective concentrations, but I suspect you don't mind a research challenge.
Starting at Wikipedia gives this list of common flocculants (some used to treat drinking water):
aluminium chlorohydrate
aluminum sulfate
calcium oxide
iron(III) chloride (ferric chloride)
iron(II) sulfate
sodium aluminate
sodium silicate

"Natural" flocculant products:

Chitosan (clarifies wine & beer according to Wikipedia)
Moringa oleifera seeds
A species of Strychnos (seeds)

So if you can find something safe, effective & available you can measure & pre-package doses for treatment. Then why not start selling you new product to less enterprising backpackers & safarists?

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