I probably have Giardia.. and it’s no fun :-(

"And this is not even to mention that the "holes" in the filter are statistically distributed as well. Probably those have an even greater dispersion of sizes. Rated 1 micron, for example, only means % of particles 1u in size that get through is X, where X is some small number believed to be safe enough."

It depends on the filter.

From the Sawyer web page –

"Each Sawyer filter is certified for ABSOLUTE microns; that means there is no pore size larger than 0.1 or 0.02 micron in size. This makes it impossible for harmful bacteria, protozoa, or cysts like E. coli, Giardia, Vibrio cholerae and Salmonella typhi (which cause Cholera and Typhoid) to pass through the Sawyer PointONE™ biological filter. At 7 log (99.99999%) the filter attains the highest level of filtration available today.

"If viruses are an issue, we offer the Point ZeroTWO Purifier (0.02 micron absolute pores). This is the first and thus far only portable purification device to physically remove viruses. And it does it at a >5.5 log (99.9997%) rate, exceeding EPA and NSF recommendations."

"You CANNOT get sick from yourself. Anything you have is already in you. Anything you do not have is not present in fecal matter, soiled clothing, or anything else you touch or ingest. It cannot happen. Illness is always an external event. (Well, 'cept cancer…)"

I've heard the opposite, i.e. that the flora and fauna in your lower digestive tract are kept separate from your upper digestive tract (e.g. stomach) by a valve system that makes sure the former don't get into the latter. When it does you can get sick.

Thus it is very important to wash your hands before food preparation, even if you are just cooking for yourself.

Can someone verify this?

… Thus it is very important to wash your hands before food preparation, even if you are just cooking for yourself.

Can someone verify this? …

Bacteria are ubiquitous (all sorts of species and strains all over us, on us, or in us), so it just makes good sense to wash hands. Fecal matter is not sterile but once out, all sorts of additional microbes can start growing on it very quickly (exponential growth – where one cell becomes two of the same cells is called binary fission). Also remember we are talking about a microscopic scale. The human immune system plays a role too, I guess.

>"flora and fauna in your lower digestive tract are kept separate from your upper digestive tract (e.g. stomach) by a valve system that makes sure the former don't get into the latter. When it does you can get sick.

Thus it is very important to wash your hands before food preparation, even if you are just cooking for yourself.

Can someone verify this?"

Yes. Your own e. coli are fine in your lower GI tract. You'd be "irregular" without them. But ingest a fair number of them and you'll be quite sick for a while.

A long-term, large-scale field experiment has been done: Rafting trips – living out of a boat on the Colorado River for 16 days with no plumbing or outhouses – used to have a fair number of sick rafters. In concert with requiring rafters to pack our all their poo (yes, the rangers check), private and guided trips went to a system of hand washing. Between the "groover" (the ammo-can you poop into) and camp, there is a wash station. You can't leave the groover without passing it. Also, there is great social pressure to use it (because others don't want to get sick) after pooping, before preparing food AND before eating (so you'd often wash hands three times in an evening. There is a 5-gallon bucket of bleached river water with a foot pump to a faucet. The faucet is over a waste-water bucket (so gray water can get dumped later). And there is alcohol-based hand sanitizer to use after soap and water. The groover and the wash station are the FIRST thing set up and the LAST thing packed up, so as to maximize usage. Since trips went to this system, sick rafters have been much rarer. But it is a combination of regulations, fines, education, hardware, procedures, peer pressure, and awareness of the consequences (helicopter rescue of a dehydrated rafter, for instance).

>"Pasteurization of water doesn't actually need 175F, it's more like 150, but it has to stay there for several minutes"

That's what I've heard from specialists in third-world water treatment. Or 140F for an hour or two. A college friend devised a little capsule of high-temp oil with a string and a washer than would invert at 140F. So if the solar tank got hot enough during the day to invert the little gadget, it was good to go. If not, you'd give it another sunny day. 17 cents of parts and no batteries required. He was playing with a tube-in-tube heat exchanger in another design, because once to temperature, the solar-heated water could be used to pre-heat more water. He was only getting 18% efficiency on the HX because, I theorized, of laminar flow (thermosiphons are slow). "Dale, what's a granular material readily available for free in the third world?" After he packed the HX with coarse sand the efficiency went to 55%.

There's another approach that's probably more broadly useful and cheaper. A PEET bottle, with no label, left in full sun for a day renders it safe to drink. A "table" of corrugated roofing, sloped towards the sun makes a convenient holder of such bottles. Just keep track of which ones have seen a day of sun. For a base-camp setting or a zero day on the river, it could save a lot of fuel and/or pumping effort.

Cut&past from wikipedia:

Exposure to sunlight has been shown to deactivate diarrhea-causing organisms in polluted drinking water. Three effects of solar radiation are believed to contribute to the inactivation of pathogenic organisms:

UV-A interferes directly with the metabolism and destroys cell structures of bacteria.
UV-A (wavelength 320–400 nm) reacts with oxygen dissolved in the water and produces highly reactive forms of oxygen (oxygen free radicals and hydrogen peroxides) that are believed to also damage pathogens.
Cumulative solar energy (including the infrared radiation component) heats the water. If the water temperatures rises above 50 °C (122 °F), the disinfection process is three times faster.
At a water temperature of about 30 °C (86 °F), a threshold solar irradiance of at least 500 W/m2 (all spectral light) is required for about 5 hours for SODIS to be efficient. This dose contains energy of 555 Wh/m2 in the range of UV-A and violet light, 350–450 nm, corresponding to about 6 hours of mid-latitude (European) midday summer sunshine.

At water temperatures higher than 45 °C (113 °F), synergistic effects of UV radiation and temperature further enhance the disinfection efficiency.

Pretty soon we will hear if Kevin is a regular guy again.

–B.G.–

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=63223&startat=80

Read through these articles and comments. DK is a microbiologist. I studied a year and a half as part of nurse training. (Hey, most nurses are FEMALE.)

Generally, you do not reinfect yourself with anything from your own body. Maybe a few parasites. The e. coli in your body is not the same strain as the one that makes you sick.

"Generally, you do not reinfect yourself with anything from your own body."

The women who have dealt with UTI/cystitis from improper wiping might disagree.

Or is that just another urban myth?

…

Getting any microorganism in a normally sterile site (blood, bladder, spinal fluid, etc.) is indeed very bad. But the GI tract is not normally sterile; we have a varied population of normal flora, and ingest bacteria when eating or kissing, just to give a couple of examples (and E. coli can be found in the mouth's normal flora, BTW, so swallowing one's own saliva may send E. coli through the upper GI tract and cause no problems). The lower GI tract is populated from the top down. Most organisms don't cause problems on their way through the tract, other than pathogenic (disease-causing) bacteria.

RodgerDodger, where was the malfunctioning "valve" in your friend? I'm guessing that somehow the "backwash" contaminated sterile areas of the body, if it reached "vital organs", perhaps through the bloodstream eventually? It sounds quite serious.

As I mentioned in the thread James cited, what medical microbiology teaches (at least when I went to school, and I'm not aware of any significant changes in thinking in this area since then) is that the mechanism of GI disease in normal healthy individuals takes place one of a couple of general ways. One may ingest pathogenic bacteria (E. coli O157:H7 serotype, Salmonella, Vibrio cholerae, for example) that either invade the intestinal mucosa or produce enterotoxins that make us sick. The other way is to ingest food that has been overgrown with bacteria that produce toxins (staph or Clostridium, for example). For more detail see: http://www.merckmanuals.com/professional/gastrointestinal_disorders/gastroenteritis/overview_of_gastroenteritis.html

All the references I've been able to find refer to the intestines as the target of these aforementioned disease process, as a result of *pathogenic* bacteria, not normal flora, and not in the upper GI tract (stomach, esophagus, mouth). It may be that ingesting a large amount of normal "garden variety" fecal flora may cause illness in a healthy individual, but I have seen nothing documenting that, what exactly the mechanism of such illness might be, or what quantity it would take to produce some sort of verifiable symptom. That's a study I won't be volunteering for, I can tell you!!!

Disclaimer: I don't consider myself primarily a microbiologist (though I did work briefly as one in a private reference lab) – rather I was a state-certified clinical lab scientist (mostly in hematology and immunohematology) in a hospital with a great microbiology department which saw pretty much everything under the sun, what with a large portion of the clientele being disadvantaged, homeless and/or immigrant: malaria, other exotic parasitic and bacterial diseases, you name it, we saw it.

…

I was guessing bile duct; that sounds like a terrible ordeal for your friend. I'm glad to hear that things turned out well in the end – whew!

I think it also needs pointing out that IF the water is very dirty the boiling times suggested might not be enough.

If the Virus or bacteria is coated in debris it can act as pretty effective insulator.

For me personally i'll always err on the side of caution after being extremely ill from drinking contaminated water.

Years ago it took a lot of time effort and energy to clean water, now with current technologies and filters it's as easy as filling a bottle.

I've never been in a car crash on a public road where the impact was severe enough that a seat belt prevented injury.
Still i wear a seatbelt every time i sit in a car.

Unfortunately we do not know when and where we will require a seat belt, just like we cannot know just by looking at it if water is safe to drink.
We can play the odds using some common sense, but still you can't remove every risk in life.

"…we cannot know just by looking at it if water is safe to drink."

But we *can* make reasonable assumptions by looking at surrounding conditions.

Turbid water at lower elevations, esp. near livestock areas? Foolish not to treat.

Clear, fast-flowing water at elevation in a wilderness area, and collected very near the source? Drinking without treatment is very low risk.

David Thomas's points about UV purification up-thread imply water within the first few inches of the surface of an alpine lake should also be safe.

I always carry an effective method of treatment, but if conditions suggest the water is very unlikely to be contaminated, I prefer not to treat.

Clear or fast flowing water makes absolutely no difference.

Sure drinking out of a muddy puddle would logically tell us is riskier, but you can and people do get ill from drinking extremely clear, fast flowing water.
Hopefully someone can back me up or call me out here, but i'm sure i read a report that stated well oxygenated water is better for certain water based bacteria/virus?

True or not we are talking microscopic here, you really have absolutely no idea just by looking at the water if it's good or bad.

Don't get me wrong, we all make our own risk assessments in our lives on a ongoing basis, it's up to each of us to weigh up what we perceive to be the risk, form a strategy and act upon it.

My point is us humans tend to only accept the full force of our decisions if something goes wrong.
I'm a prime example, i was extremely cautious to the point of being anal about where i took my water from, i made fun of my mate who was treating and boiling his water, to me then it was a macho thing "look at me i laugh in the face of microscopic bacteria/virus"

I fell extremely hard from my high horse, having been through that i will do what ever is in my power to prevent it again, even IF it's a 1 in a billion chance.

With modern filtering your reducing the chances for no real gain in hassle and very little financial cost, so to me why wouldn't i filter all my water?

I think clear and fast flowing is correlated with few parasites.

If you did a survey of many water sources, those that were clear and fast flowing would be more likely to be on some mountain, near the source, less likely to be contaminated. Higher on a mountain there are fewer animals.

Those water sources that are slower and dirtier looking, are more likely to be downstream of animals pooping or whatever.

The parasites in water aren't visible and the fast flow of a stream does not kill parasites.

When I'm on some mountain and the water looks clean and it's fast flowing, I often don't treat it, and have never got sick that I know of. But the Squeeze is so convenient I've been treating more often. Maybe I've just been lucky in the past.

Some article on BPL talked about this.

When (or if) backcountry water is safe to drink without treatment has been endlessly debated on these forums.

The key requirement for what I suggested was very low risk water isn't "clear" or "fast-flowing" but "at elevation in a [designated] wilderness area," (e.g. not the Appalachian Trail, or on rangeland); and "collected very near the source," (e.g., I know it's coming out of the ground without crossing human or game trails before the point of collection). Does that describe the water that made you ill?

"Clear" *does* mean the water has no algal or bacterial biofilms. "Fast-flowing" (if close to an underground source) *does* mean the water is likely to be as cold as it was coming out of the ground. It's been a long time since I had a food handler's card, but IIRC, cold temps inhibit the growth of pathogenic bacteria.

The risk of waterborne viruses in the American backcountry is virtually zero. And (again, IIRC) the organisms of most concern in backcountry water aren't bacteria, but giardia and cryptosporidium. The CDC says both parasites are spread by fecal matter–water under conditions where I would likely drink it untreated is *visibly* very, very unlikely to be contaminated by human or animal feces.

This isn't about being macho, or laughing in the face of danger, it's about rational risk assessment. It's also about cultivating a philosophical attitude that wild nature, while certainly indifferent to me, is not an actively hostile force I need always protect myself from. For me, an antidote to a "pack your fears" approach to wilderness is worth the (very slight) risk of drinking raw water under particular conditions. Others may make a different choice, of course.

I assume your "1 in a billion chance" remark was meant hyperbolically, since the best filters still won't get the last one out of every billion organisms in a contaminated source. And you'd have to drink "1 in a billion chance" raw water every waking second of your life to have even odds of catching anything.

"I think it also needs pointing out that IF the water is very dirty the boiling times suggested might not be enough.

"If the Virus or bacteria is coated in debris it can act as pretty effective insulator."

Water is an excellent conductor of heat. If the debris is permeable to water (like slime) it's going to be as hot as the water. As long as your water doesn't have massive floaters, you'll be fine.

What sort of hypothetical "insulator" are you imagining?

"David Thomas's points about UV purification up-thread imply water within the first few inches of the surface of an alpine lake should also be safe."

Has been my SOP for years when taking water from high altitude lakes in the Sierra. No problems so far. That said, there are high altitude lakes where horse packers have let their horses crap on the lake shore, and there I treat just to be sure. I don't know if horse manure is as pathogenic as cow manure, but I prefer prudence over being a guinea pig.

"I always carry an effective method of treatment, but if conditions suggest the water is very unlikely to be contaminated, I prefer not to treat."

+1 at the risk of reigniting The Great Rockwell Flame War. ;0)

"you really have absolutely no idea just by looking at the water if it's good or bad."

True enough, but people can and do successfully assess the potablity of water by evaluating the surroundings.

Some good points.

While i agree a good filters isn't an absolute guarantee i don't think anyone could argue it doesn't dramatically reduce the risk.

Elevation may reduce the risk, if water rat has been running past the area your collecting water though, if a dead bird is a few meters upstream, dead fox, rabbit, they could even be frozen and defrosting upstream as you're drinking.

I've even seen campers swimming in mountain top lakes and streams, i've found evidence of people urinating into high streams and defecating.

I do agree that if given a choice i would prefer to drink untreated water from a fast flowing stream, rather than a muddy puddle, i personally believe from my personal experiences that the risks are higher than you believe they are.

As i say though unless we as humans experience something first hand we tend to discount logic and others experience, so i do understand.
A girl i used to work with contracted HIV by having unprotected sex, she she's she did it once and didn't push the point about using protection as she felt the experience would be better.
I'm not comparing getting a nasty stomach bug to contracting a deadly, life changing disease, just pointing out that nature doesn't care about what people want or have done before.

Sorry if i come off a bit preachy, that's not my intention, as i say we're all adults and we all carry out own risk assessments continuously.

It's just having been extremely ill from suspected water (yes it was taken from a high source, was clean and fast flowing) and with modern filters being so cheap and easy to use i just think even IF it only slightly reduces the risk it's crazy not to use one.

I respect your philosophy though and have no chance or intention of trying to change your mind, i have my fingers crossed i can get some folks to think twice and research the risks and solutions.

There are a number of studies that indicate that many instances of gastrointestinal illness were as likely (if not more likely) to be caused by poor hygiene as by 'bad' water. It is always amazing to me to see the amount of folks folks who are completely anal about their water treatment routing but don't wash their hands before preparing or eating a meal, or wash their cookware afterwards!

Jim, I'd be interested in reading those studies if you can list them, and where they might be found.

Well, as far as scientiffically designed studies, I have only seen a few, but they do not count. They were done in hospital's on disease communication/vectors. Most diseases are studied that way.

It is nearly impossible to tell if water is safe to drink or not. Yes, you can evaluate the surrounding area. You can MINIMIZE your risk. Filters only minimize the risk. Chemicals, too. UV, and solar, also. Boiling is perhaps the safest. You are subjected to constant exposure to a lot of different bacteria all day long.

As DK said, I would be interested in any scientific studies and papers, also.

Washing cookwear? Well, I don't really do that either.I rinse it out with wild water, then I dry it out with my dirty bandana. I don't try to get it scubbed bright and clean. It is boiled every 10-14 hours, thats as clean or more so than at home. Bacteria and spores take time to form. Drying it out means most die because water was removed. It will take 24 hours for anything grow on it to the point of making me sick, even if I didn't rinse and dry it and made sure to leave it in a warm, dark place. I have eaten twigs and bugs in my water after boiling. I wouldn't say this is something to worry about. At least I haven't been sick from this yet. But this is not a scintific study by any means.

If you eat out of your pot you don't have to worry about it. Wash it off when done. When youu next use it and heat water in it, it will be disinfect it.

Of course there's your spoon – wash it off so there's no organic matter, then the next time you stir up your hot food in boiling water it will disinfect it.