Apr 20, 2008 at 2:53 pm #1228481
Rather than rely on purification products' manufacturer's data or reviews of water treatment products that essentially say, "I used this product to purify my water and I didn't get sick." –which could mean the product worked, or the reviewer has a strong immune system, or just as likely that disease pathogens were absent from the water — I opted to research impartial, informed sources.
I found a nice report at the Centers for Disease Control (CDC) website that discussed the efficacy of sodium hypochlorite (NaOCl) (household bleach) against bacteria, protozoa and viruses. NaOCl has long been used as an emergency water treatment and as an alternative to gaseous Chlorine disinfectant in municipal water systems.
The bottom line was that the proper dosage and exposure time to sodium hypochlorite would inactivate all the pathogens except the oocysts of toxoplasma and cryptosporidium. I haven’t found any chemical treatment that completely inactivates these oocysts, but fortunately both are removable by readily available (and portable) sub-micron filters. If chemical treatment is to be relied upon, it’s clear it should be followed by filtering. Filtering alone is not effective because it can’t remove viruses which the bleach will inactivate.
The dosage for clear water recommended by the CDC report was 1.875mgNaOCl/L. The Clorox website recommended a half hour exposure to 2 drops of bleach per liter. I made a calculation based on the weight of 50 drops = approx 3 grams of 6% NaOCl. I calculated that the two drops contain 7.2mg NaOCl. This is significantly higher than the dosages tabulated by the CDC report, but is the same amount as recommended by the Environmental Protection Agency (according to Wikipedia article on chlorine treatment).
Using these numbers, I calculated that a gallon of plain bleach (you don't want to use scented or otherwise modified bleach for disinfecting drinking water) will treat about 31000 liters of water. Clorox costs about $2.50 per gallon making the cost of treatment 0.0075 cents per liter. That means one penny treats 133 liters of water.
As a comparison, I saw 24 chlorine dioxide purification tablets (1 tablet per liter) priced at $14. That comes to 58.3 cents per liter, or treating your water with chlorine dioxide costs 7800 times more than bleach treatment costs. The tablets also require 8 times longer exposure to the pathogens.
There’s another advantage to using bleach. You can smell excess bleach. If you don’t smell the bleach after treating the water, it means all the bleach was used and there may be unaffected pathogens remaining. It’s a good indicator that you need to re-treat.
The big downside of using bleach is the bad taste it imparts to the water. However, after the treatment interval, the bleach can be removed by a charcoal filter. This doesn’t impose an additional burden since all chemically treated water should be filtered to remove oocysts. Just choose a submicron filter that also has a charcoal element. The final result is fresh, clean tasting water at a savings few can ignore.Apr 20, 2008 at 4:46 pm #1429274
I've read the CDC stuff before and chlorine is said to be the most used worlwide. But, chlorine dioxide is still the best all around chemical water treatment and does inactivate cryptosporidia.Apr 20, 2008 at 5:24 pm #1429277
I read an EPA report that says chlorine dioxide can't be relied on to inactivate oocysts completely. Post treatment filtering affords additional safety. If you filter, there appears to be no advantage to chlorine dioxide. Given the outrageous cost ratio, I know what my decision is going to be.Apr 20, 2008 at 5:49 pm #1429281
@pwise757Locale: Northeast USA
I must first admit that I have yet to rely completely on water purification since my trips have not lasted more than two nights since 1978. If you are carrying clorox and a charcol filter, isn't that heavier then the tablets?Apr 20, 2008 at 7:52 pm #1429293
@walksoftlyLocale: Piney Woods
I came upon a purification method a few years ago that has served me quite well.
1) Scoop up water in a 16 oz. platy bottle with the top cut off. Makes a great lighweight cup.
2) Filter through bandana into water container. Gets rid of the floaties.
3) Use MP1 tablet for 15 minutes to get rid of bacteria & viruses.
4) Use McNett frontier straw (I keep it in a knife sheath) to filter out cysts and remove any foul taste.
It may seem busy, but it is lightweight and I never have to wait over 15 minutes for a drink.Apr 20, 2008 at 7:54 pm #1429294
What's MP1?Apr 20, 2008 at 7:57 pm #1429296
@back2basicsLocale: Southeast USA
MP1 = MicroPurApr 20, 2008 at 8:00 pm #1429297
We've always filtered no matter what for safety and taste so the weight's about the same either way except we usually carry way more Clorox than we need because it's so cheap we can afford to purify all our water, not just what we drink.Apr 21, 2008 at 7:34 am #1429318
MP1 is Katadyn Micropur MP1 chlorine dioxide tablets. Herman, do you have a link to the EPA report?Apr 21, 2008 at 8:10 pm #1429426
I'm sorry I didn't save links to the EPA reports. Try the wikipedia on sodium hypochlorite. It might have some references to EPA reports.
The most useful report I found was at the CDC. It's available in PDF form. Try searching for "Safe Water System" at the CDC web site.Apr 25, 2008 at 12:16 am #1430105
@erothman2Locale: Pacific NW
Was thinking I'd go with the 2-part liquid stuff, but that seychelle filter sounds sweet and fast, and no city-water taste. Anybody here tried it?Apr 30, 2008 at 12:58 pm #1430925
Which Seychelle filter are you referring to?May 5, 2008 at 12:19 am #1431648
Iodine tabs (Potable Aqua) have long been considered to be reliable for back country water purification. Chlorine dioxide, in all its forms available, seems to have superseded iodine tabs as the "premo" chemical treatment for backpacking water. That being said, I personally love iodine tabs and will always fall back on them. Iodine tabs are ridiculously cheap, you can buy them almost anywhere, have been around forever so the side effects are well known and simply work well.
Quite frankly, I think you over analyze and you need to go back to the basics. Bleach is not considered a mainstream method of purifying backpacking water.
EricMay 7, 2008 at 2:58 pm #1432080
@hikin_jimLocale: Orange County, CA, USA
Iodine doesn't work against cryptosporidium. Crypto isn't all that common in N America, but it's something to throw into the mix as you consider how to treat water — if you treat water. There have been a lot of studies that indicate that the giardia scare is just that, a scare, and that in wilderness areas in N America the incidence of giardia is quite low, particularly in the West. I still drink straight out of streams on occasion, IF there aren't any human activities upstream and it's in a fairly low use area.Jul 3, 2008 at 5:04 pm #1441407
@jmeeksLocale: North Carolina
I could use some advice or recommendations on the first need xl or deluxe. Is there a difference between the two, and does it work well? Thanks!Jul 3, 2008 at 7:25 pm #1441422
I have 2 of the Deluxe filters. They were originally bought for a location-shoot in Mexico but I've used them on a few short backpacking trips. I bought the optional pre-filter and used it 100% of the time.
In a pre-purchase review of the Deluxe, someone said "it can make a mud-puddle taste like a glass of 'Evian'". I agree. It produces the best-tasting water I've had in the wild from questionable sources.
If you're in an area where you can get very-clear water, it is one of the fastest ways to purify a few liters of water.
The device is a stand-alone pump attached to a replaceable/disposable cartridge that contains a "structured matrix"TM. The pump pushes non-purified water into the cartridge. I used one of the pumps to push water through a lighter, non-purifying filter with some success, but ultimately decided that it was still over-all too heavy to carry in my kit.
I don't know about the XL you mention.
The "cons" (for me) outweighed the "pros". (my experience and opinion, your mileage may vary)
1. It is really heavy. 15 oz or 430 grams (per manufacturer) when it's DRY, more once you've used it as water stays inside the filter material. If you're paddling or base-camping, that's not so bad, but for a UL walker, forget it.
2. I did have to pump from a "muddy" lake on one trip, and after only a few liters I had to "field backwash" to clear the "matrix" or filter with some of the purified water I wanted to drink. This yielded another 3/4 liter before I had to repeat the process. Now, the water we had pumped was very rich in clay-like dissolved soils and it even clogged the pre-filter. In retrospect I'd probably just have boiled this water and allowed the solids to settle out afterward instead of filtering, but when you're carrying a pound of filter, you want to utilize it.
3. Once the "matrix" clogged, we learned to stop trying to "pump" water, and go to a gravity feed to move water through the filter. An expedition member force-pumped, and ruptured the "matrix" on one of the units. You can't always tell you've done so unless you do a "field" test with the included dropper of blue dye. (sound like something you'd like to try in the dark at the end of a long day?) In this case we saw muddy water in the platy and didn't need to do the test.
4. We tried the Gravity feed option, and while it worked, it was very slow and cumbersome in comparison to pumping. At this point, we decided to chuck the (nearly one-pound) filters into the bottom of our backpacks and started using the bandana and chlorine dioxide we'd brought as a back-up.
In my experience, most of the "life" and use of the cartridge occurs in gravity-feed mode after it becomes too hard to pump water through the filter cartridge. Also, in my experience, once you have to "backflush", the pumping is pretty much over with with that cartridge.
It could be that with clear or near-clear sources, this might not happen so soon. If you're in an extended base-camp environment, this might be fine. You could also do a gravity feed while you slept for fresh water in the morning. Only you can decide if it's worth the weight.
Bottom line for me: Short useful life and too heavy.
Back at home, I figured the $47 it cost to replace the ruptured cartridge would buy lot of real Evian from le France, or a heck of a lot of UL style water-treatment.
I hope this helps!
BarthJul 4, 2008 at 2:14 am #1441456
@jmeeksLocale: North Carolina
I sincerely appreciate the quick thorough response. You have given me much to think about. I am not too sure what kind of water I will need to purify at Philmont Scout Ranch but will look into it. Thanks again.Jul 5, 2008 at 2:21 am #1441563
The differences between a purifier and a filter.
Filter – removes bacteria.
Purifier – removes bacteria and kills viruses.
Most of the time a filter will do just fine. But it depends on “where” you are going. If you are going to a third world country, then get a purifier. If you are hiking here in the USA or most of Europe, then a filter should do.
The water quality has a lot to do with the types of sewage systems in the area. Most modern nations use a closed sewage system, meaning that raw sewage is not dumped into the local water supply.
Filters are cheaper. You can get one for less then $100. Purifiers cost a little more, maybe 150+. Its been a long time since I have checked prices on purifiers.
Over the past 10 years I have seen a serious decline of purifiers on the market. Most of them today I would not buy. In the late 1990s, purifiers were the “in” thing, now they are hard to find.
If there is a chance your water is infected with viruses, use a filter to remove the heavy organic matter. Then use some iodine tablets to kill any viruses. This might be the most cost effective way. It beats spending the price difference between a filter and purifier.
Most water purifiers require you to wait about 30 minutes from treatment to drinking. this is to make sure the chemicals have time to kill the viruses. Most of these chemicals are iodine or chlorine based. There are some UV lights on the market that are supposed to kill bacteria and viruses. Use a filter to remove organic matter and then use the light to kill bacteria and viruses.
To kill viruses, add some iodine tablets to the container and wait 30 minutes, or use a UV light. Water filtration and purification should be 2 steps – filter and some kind of chemical (or UV light) to kill the remaining virus or bacteria.
One of the cheapest filters on the market is the Katadyn Hiker PRO Water Microfilter.
Just because these filters are inexpensive, does not mean they are of poor quality. Katadyn produces some of the best filters on the market and at prices that will not break the pocket book.
If the extra weight and cost of a water filter is a problem, then the hiker can use a bandana, clean sock or a clean shirt to remove heavy organic matter. Then, with the addition of some water purification tablets – wait about 30 minutes and the water should be safe to drink.
You may compare between Fliter and purifier at amazon.com via below linkJul 5, 2008 at 9:23 pm #1441674
I took a 1.8 oz. in-line filter with a Platy "hoser" set-up to Philmont last year.
After chatting with our Ranger, I left the filter in Base Camp. Most of the time we had potable water from staffed camps, or we just dipped out of an alpine stream and used the Philmont-provided Micropur chlorine dioxide tablets.
Last year Philmont issued 10 tablets to every trekker, and you turn in the empty foil at any staffed camp for a replacement pack.
According to the rangers, the biggest worry there is E. coli from cattle on the ranch. Viruses aren't an issue, thus the First Need is over-kill.
I'd recommend you take one 1 liter and one 2 liter Platypus bags for water. I never carried more than 2 liters, but I was in the north where water is plentiful. Most of our Scouts used 2 Nalgene 1l bottles.
The other point I'd offer about Philmont is that the Rangers try to foster an environment where advisors are "on vacation" while there. They want the Scouts, through the Crew Leader, to figure out a duty roster, including water gathering and purification. Standardizing on the 1 tablet per liter Micropur makes this easier for the Scouts to accomplish in a routine fashion without mistakes.
Good luck and good trekking!
BarthJul 8, 2008 at 2:58 pm #1442042
It's great to look at studies by CDC and WHO, but it all needs to be taken in context.
This is a hot topic in my mind. I spent my first five years of backpacking without treating any water. Then a friend read an article about Giardia, USFS started posting warnings based on possibilities, and Katadyn stepped in with advertising in the magazines. In the 20+ years since I have always treated the water by microfiltration and/or chemical treatment. A few weeks ago I took my kids on their first backpack trip and I pumped all their water.
I have used the same protocol whether the water came from the Magdalena River downstream of Bogota Colombia, taps in Baja or 33 degree snowmelt at 12,000 feet in the Sierra.
Recent reading of articles specific to the high Sierra between Yosemite and Sequoia indicate that the panic for this region was mostly unfounded. Here are my conclusions:
Largest risk is poor sanitation habits by members of your own party. Using alcohol hand sanitizer after pooping and before touching food will eliminate more cases of the runs than all the water purification technology on earth. My solo hike eliminates this risk since I can't catch anything from myself.
For water borne pathogens these are some generalized risks:
Viruses: No risk. Nada. Zilch. This is 10,000 feet in the Sierra, not at the Ganges' mouth!
Cryptosporidia: No reported cases, no measured contamination.
Giardia: Drumroll please… Insignificant risk, or at least close to it.
Bacteria: Still low, but by far the most likely source of problems.
With this information, my decision whether or not to purify, and how to purify, has changed. Best sources for water are different with lake outlets having fewer bacteria than inlets. If you eliminate concern over viruses and cysts then the performance of chemical purification changes. Bacteria is killed quickly, and the reduced performance in colder water is offset by the lower liklihood that significant numbers of bacteria will be found in colder water.
Luckily there is no commercial cattle or sheep grazing upstream of the whole JMT. Tests of pack stock manure showed fairly low, but still significant rates of potentially harmful E-coli bacteria.
My plan for water treatment on my JMT hike is this:
1. Drink smart. Pay attention to the route water took and whether heavy human use, pack stock use, or pack stock grazing is likely upstream.
2. Chemically treat any suspect water, but use contact time based on killing bacteria not cysts.
3. Presume specific location contamination identified by Derlet to still exist, avoid these and similar areas.
4. Drink heavily from good water sources, avoid or treat suspect sources.
5. Treat all water between Yosemite Valley and Tuolume Meadows; near Blaney Meadows; and whenever I have to draw water from a source that has significant use and trail crossings upstream.
I'll let you all know how it worked out.
Here are my sources, plus lots of unsubstantiated forum banter. Remember this only applies to the national park and USFS wilderness areas near the John Muir Trail.
Abstract only for the following article free online- I haven't seen the full text:
Risk Factors for Coliform Bacteria in Backcountry Lakes and Streams in the Sierra Nevada Mountains: A 5-Year Study
Robert W. Derlet, MD; K. Ali Ger; John R. Richards, MD; James R. Carlson, PhD. Wilderness and Environmental Medicine: Vol. 19, No. 2, pp. 82–90.
Complete text for the following can be found online:
Giardia Lamblia and Giardiasis With Particular Attention to the Sierra Nevada By Robert L. Rockwell, PhD. Sierra Nature Notes, Volume 2, January 2002 (rev. May 2002)
High Sierra Water: What is in the H20? Robert W. Derlet, MD. Sierra Nature Notes, Volume 3, April 2004
Coliform Bacteria in Sierra Nevada Wilderness Lakes and Streams: What Is the Impact of Backpackers, Pack Animals, and Cattle?. Derlet, Robert W., Carlson, James R. 2006: Wilderness and Environmental Medicine: Vol. 17, No. 1, pp. 15–20.
An Analysis of Wilderness Water in Kings Canyon, Sequoia, and Yosemite National Parks for Coliform and Pathologic Bacteria. Derlet, Robert W., Carlson, James R. 2004: Wilderness and Environmental Medicine: Vol. 15, No. 4, pp. 238–244.
Coliform and Pathologic Bacteria in Sierra Nevada National Forest Wilderness Area Lakes and Streams. Derlet, Robert W., Carlson, James R., Noponen, Mikla N. 2004: Wilderness and Environmental Medicine: Vol. 15, No. 4, pp. 245–249
Derlet, Robert Wayne, Carlson, James Reynolds. 2002: An Analysis of Human Pathogens Found in Horse/Mule Manure Along the John Muir Trail in Kings Canyon and Sequoia and Yosemite National Parks. Wilderness and Environmental Medicine: Vol. 13, No. 2, pp. 113–118.
You must be logged in to reply to this topic.