Water Filters?

[Peaks]

There are several threads on water treatment. Just like all gear, one method, or product does not work best for everyone. Some use chemical, some use filters, some use UV, some don't treat at all. There are trade-offs with each method. So, do your research, and then make a decision.

[Tinker]

I use a First Need filter. It's heavy and bulky vs. the more popular filters on the market, but it removes viruses as well as bacteria. I began to rethink how I treat cooking water lately. I used to just take it out of a stream or pond and boil it while making dinner. When rehydrating food in the summer, filtering first eliminates the need to bring water to a boil, so you can make hot drinks using less fuel, and rehydrate foods at a lower temperature.
In short, I filter more so I use less fuel.

[Panzer1]

Mueser cites other studies, opinions of scientists with whom he spoke, etc. I've seen no better study that relates to this specific topic, as it applies to AT thru-hikers.

I will agree with you that I've not seen anything better than this either, but this just isn't really a "study" its a survey.

Panzer

[Critterman]

I will agree with you that I've not seen anything better than this either, but this just isn't really a "study" its a survey.

Panzer

I reread the book a couple of weeks ago and I have to agree with you. Another thing to consider is that in 1989 there was no Aqua Mira and 43% of the people he surveyed were using iodine which is the least effective chemical disinfectant. Only 14% reported always using a disinfection agent or filter.

[rafe]

Here's Mueser (P. 98)

"The sample sizes in this study are small, and one is tempted to dismiss the results for this reason. But it should be noted that although the data are from a total of only about 136 people, we are measuring this phenomenon over an extended period of time -- some 15,000 person-days of backpacking during which time the hikers sampled about 1,000 water sources with each person "testing" several hundred sources in the course of a hike. This is no simple compilation of the sickness rate of a few friends hiking over a weekend. The reported cases of sickness may only be 41, but the basic exposure and variety of sources are extensive."
...

"These findings are not the first to hint that how hikers purify their water and how often they do so may or may not be the critical factor in contracting gastrointestinal illness." Mueser then cites a 1993 article in The Journal of Family Practice, based on 180 thru-hikers in 1987-1988, by Byron Crouse and David Josephs.

Table 13-2, P. 95: Methods of Water Purification Used by Hikers

Method : Number of Hikers using Method : Percent of Total

Iodine : 57 : 43
Filtering : 40 : 30
Boiling : 15 : 11
Chlorine : 4 : 3
No Treatment : 18 : 13
Total : 134 : 100

Table 13-3, P. 96: Type of Purification Method vs. Frequency of Gastrointestinal Illness experienced on the trail

Purification Method : Percent of Users who became ill : Giardia only

Iodine : 26 : 6
Filtering : 30 : 9
Boiling : 34 : 3
Chlorine : 75 : 0
No treatment : 27 : 3
Average : 30 : 6

Table 13-5, P. 98: Frequency of Water Purification Versus incidence of Gastrointestinal illness

How Often Purified : Number of Hikers : Number Ill : Percent Ill

Always : 19 : 4 : 21
Usually : 36 : 10 : 28
Sometimes : 56 : 22 : 39
Never : 25 : 5 : 20

Mueser himself finds the results difficult to explain -- though he spends a few pages trying. I won't give it away. Get the book. It's great read.

[Wise Old Owl]

I agree with jersey joe that most drinking water can be had from little springs with no treatment. BUT.

There are many spring sources where heavy camping occurs, and unless you're careful about following the source upstream beyond human impact, getting water at some of these heavily used sites(mostly around shelters)can be a problem.



I've found the old Pur/now Katadyn Hiker filter to be fast-flowing and good though I've broken the handle off of it twice. On my last trip I used a Katadyn mini-filter(the little blue thing)and it took me about 150 pumps for a liter, much slower than the Hiker.

Samething - Sweetwater broke at the worst possible moment, You know when it breaks the water bursts out the top of the handle. I now use Katadyn Hiker

[Panzer1]

Although this survey is about treating water and the % of hikers who got sick, we have no way of knowing how the hikers got sick. It may have been from the water or it could have been from dirty hands, dirty cookware, contact with infected persons, expired food, ect.

These other causes could cause the percents to be skewed. For example if the % of illness among hikers who "always" treated water was 21% then those 21% must have become infected not from the water but from some other source. That's what I would guess as long as they were treating their water properly, which we have no real way of knowing.

There is a pattern where the "sometimes" group had a higher illness rate that the "usually" group. The "sometimes" group has almost double the illness rate of the "always" group which is what I would expect. The trend here is that treating water reduces the infection rate.

The "never" group breaks the trend and has a lower illness rate by 1 % which does not seem right after looking at the trend in the previous 3 groups.

From looking at this survey it is far from "clear" what the effect of treating water has on the % of illness. If anything it only causes more confusion because the "never" results contradict the the other 3 groups.

Most surveys have a "margin of error". He does not say what he thinks his "margin of error" is in this survey.

It is possible that some people in the "never" class have build up a resistance to gastrointestinal infections from prior infections.
This could skew the percentages.


Panzer

[rpettit]

This is an example of the type of study that is valid. http://www.pubmedcentral.nih.gov/art...?artid=1349767

I would not make any decision on if I should treat water or with what to treat water based on Mueser's survey. Asking people to self diagnose at the trailhead is completely out of of control. You cannot diagnose Giardia through symptoms. You have to take a stool sample, stain it with a specific chemical and view the sample under a microsope to identify the organism. Mueser's study is invalid, and publishing the erroneous data is irresponsible.

[Critterman]

............................... That's what I would guess as long as they were treating their water properly, which we have no real way of knowing........................Panzer

I think it would be really interesting to know how many hikers actually do use the proper technique when using their chosen method of disinfection. Do people use the right amount of chemical and wait the required time before using the water after adding a chemical? If not then it would not be surprising that the "never treat" and the "always treat" would have the same rate of problems. Another thing that really makes everything clear as mud in the book is that only 14% always treated their water and he doesn't tell you what methods those 14% used.

[CherrypieScout]

I used to carry filters - too much weight for the benefit. Now I carry MSR tablets and a couple of coffee filters. THe best suggestion I've ever heard and now follow is to use hand sanitizer before every meal and after every potty break - especially after using the nasty privys. A small bottle will last for 2 weeks.

[zoidfu]

Whatever you do, don't get a steripen. They eat batteries like there's no tomorrow and the bulbs break easily. I broke two of them and to this day I don't know how I did it. I'm not a go liter, that said, I like the Katadyn hiker pro.

[Panzer1]

One thing that surprised me was that among hikers that boiled, 3 hikers still got sick. I would have thought that boiling would in theory be the method that would be guaranteed to kill everything.

Panzer

[Tipi Walter]

Whatever you do, don't get a steripen. They eat batteries like there's no tomorrow and the bulbs break easily. I broke two of them and to this day I don't know how I did it. I'm not a go liter, that said, I like the Katadyn hiker pro.

Thanks for the input. I've been eyeballing the steripen for a while, thinking it would be a viable alternative in zero degrees, but something held me back. In the winter I usually dip and drink, sometimes boil, as a filter can't be used in the frigid temps. Don't think I'd want to rely on the steripen, either.

[elray]

MSR has just introduced a new lightweight high flow model available beginning this month. I'm going to check it out. I've been very happy with the Hiker Pro up till now but it is a slowpoke. Here's a review of the MSR Hyperflow.
http://www.trailspace.com/gear/msr/h...w-microfilter/

[Wise Old Owl]

Well ...with a trail/screen name of "Neurosis" I would guess you might have relatively high level concerns about water purity ???

In the end only YOU can decide which method makes you feel most safe. I've gone through ALL available methods, starting with filters - then PolarPur and finally AquaMira.

Over time I grew increasingly concerned about the true efficacy of mechanical filters - especially when being used many times during each day for weeks/months on end. There is fairly good potential for cross-contamination of the input/output hoses AND ...the filter element (which traps the contaminants) sits inside the filter housing and stays damp throughout it's use -- a perfect environment for the growth of bacteria and other pathogens.

I am personally comfortable with chemical treatment (AquaMira) and use it exclusively nowadays.

'Slogger

I got forced into using several brands over the years as some of you allready know (i am allergic to iodine) and most of the pipes are both labled and are different sizes to prevent mixups and cross contamination. Some will include a kit to connect direct to some bladders and bottles to really keep it simple. What I quickly learned though, the larger the filter the easier it is to pump. The other learning skill is to add a little more boiling water to the dehydrated food as it tends to bind you up. The only reason for all this trouble is avoid getting explosivly sick in the woods.

And Slogger, the next time I go out I am going to give AquaMira a try.


I watched one of my canoing partners stay hydrated with this little light weight KATADYN WATER BOTTLE MICROFILTER He drank right from the river. He stayed hydrated, clipped it to the useless Ice axe loops, and never bothered to ask for the group filter. You can't cook with it, it weights 7-8 oz wet without water and it works. You do not have to hike with the water in it. He would fill it up in a stream and drink then dump. You must read the instructions on this products first use.

[Wise Old Owl]

One thing that surprised me was that among hikers that boiled, 3 hikers still got sick. I would have thought that boiling would in theory be the method that would be guaranteed to kill everything.

Panzer

Yea but you kind of gave us the answer, they more likely got sick from the outhouse or shanking hands then the water.

[Panzer1]

Yea but you kind of gave us the answer, they more likely got sick from the outhouse or shanking hands then the water.

Yes, that's what I'm thinking. That's why I think the entire survey is not scientific enough to use. Probably, there never will be a scientific enough study to make everyone happy. That's why in the end people will do whatever they want. Nobody will ever have enough evidence to prove their point or to change someone's else mind.
Still, I think that the survey is interesting.

Panzer

[russb]

Thanks for the input. I've been eyeballing the steripen for a while, thinking it would be a viable alternative in zero degrees, but something held me back. In the winter I usually dip and drink, sometimes boil, as a filter can't be used in the frigid temps. Don't think I'd want to rely on the steripen, either.

I have the steripen, no problems whatsoever. YMMV

[fonsie]

http://www.msrgear.com/watertreatment/hyperflow.asp
Check out the new hiper flow...7.4 ounces not bad considering I been useing the msr mini works for a few years now that weighs 15 ounces.

[rafe]

Although this survey is about treating water and the % of hikers who got sick, we have no way of knowing how the hikers got sick. It may have been from the water or it could have been from dirty hands, dirty cookware, contact with infected persons, expired food, ect.

Pretty much. Mueser speculates that it's something other than water that caused the illnesses. And you know, there are several WBers each with many thousands of miles who claim to never treat their water. Something to ponder, anyway. I carry a filter nowadays, but for the first 15 years or so, I didn't.