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View Full Version : Water filters and treatment discussion..Part 1, source and filters.



Lawn Sale
04-23-2006, 02:40 AM
This is the tangential thread on water filters from the "bad gear" thread. I figured I'd start it with the hopes of quelling many misconceptions before they escalate.

I figured it was about time to start the "water filter" thread anyway as the winter hiking season is over :(



Obtaining potable (safe) water while on the trail, Part 1

The purpose of this segment is to clarify how to obtain clean water while on the trail. I have purposefully omitted many areas of water filtration and disinfection because they do not readily pertain to hiking, and there is enough to chew on and digest already. I could go on for days about different techniques as they pertain to different areas, but since I donít want to write a dissertation and you donít want to read one, Iíll keep it as simple as I can.

The problem is how to get safe drinking water from supplies on the trail. The solution is a two-stage process, but letís go into source supply first, since thatís where it all begins.

I have been hiking for many years, and always hear people say, ďthis is safeĒ, or ďthat is unsafeĒ when they donít really have a clue. The proper rule of thumb is that no water is safe to drink. There, that was easy. What about springs you say? How do you know if the spring is fed by surface water? Itís impossible to tell when youíre tramping by. There is even an acronym the EPA uses for regulations, called GWUDISW (or just GWI in Canada), which stands for Groundwater Under the Direct Influence of Surface Water. How can you tell? You canít, but those of us with laboratories can, which is all that matters. What about running water, there are still some old myths around that say running water is safe to drink. Sorry, itís just that, a myth. Running water mixes contaminants so youíre even more likely to grab a sample of something nasty from a stream (although some viruses are more prevalent in ponds). The myth most likely originated from the jungles of Panama where stagnant water would breed malaria and anaerobic organisms due to the lack of oxygen added from the mixing provided by movement.

Some people are going to say they never got sick doing X or Y, and place A or B is known to be safe in the past. The problem here is that people and places change. Some people have a naturally high immune system, so they may not get sick while the person next to them could, despite drinking from the same water source. And no, there is no way to build up a resistance to the organisms, so donít ingest them on purpose thinking along the same lines as the flu shot. In fact, most people develop more frostbite like systems, where you are less immunized against them if youíve gotten sick from them in the past. Therefore prudence dictates trying to avoid getting sick the first time.

But, there will always be some people that say you donít need to purify the water, that the immune system can handle it and that we are too cautious. No problem, see you on the trail. But, to those who donít like playing Russian Roulette with their immune and digestive systems, this article is for you.

Potable water is relatively easy to make on the trail thanks to the popularity of hiking. Hand filters, smaller disinfection systems, and technological advances have greatly reduced the exposure to the organisms, and microbiological testing has allowed us to more easily categorize and treat the problems when people are infected. It has been said the problems with water are relatively new and that people 30 years ago didnít used to get sick. This is bunk in my mind as there were less people hiking and fewer trails to hike on, so naturally fewer people got sick, or it was chalked up to bad food or some other source. At any rate, hereís how to obtain safe water.

There are three areas of target organisms to worry about. I wonít go into contamination (pesticides, MTBE, etc) or characteristics (pH, alkalinity, etc) as there is little you can do in the field to change them and they are minor by comparison. I also wonít go into the literally hundreds of individual organisms, except Crypto and Giardia, as they are the hardest to combat. If these are killed, then pretty much everything else is killed as well, which is why they get so much attention.

1. Viruses: Viruses range in size from 0.01 to 0.1 Ķm (microns, or 1/1,000 of a mm) and are species specific with respect to infection. Escherichia Coliform (E. Coli) and Fecal Coliform (Fecals) are in this group and very prevalent in potential water supplies.
2. Bacteria: Bacteria are single celled organisms ranging in size from 0.1 to 10 Ķm.
3. Protozoa: Protozoa range in size from 1 to 20 Ķm. Crypto (Cryptosporidium Muris and Parvum) and Giardia (Giardia Lamblia) are in this group.

Right off the bat youíll notice the size differences in the organisms. This is why filtering comes into play in hiking. Yes, the filters do add weight to a pack, but theyíre necessary in my opinion and one of the heavier ones (Waterworks) only weighs 17.2 ounces complete.

Most filters will remove down to 0.3 microns, which is all of the protozoa and most of the bacteria. But, it wonít remove viruses, which is why you need to disinfect using a method Iíll describe in another section. But which filter to choose, there are so many! The answer is simple, choose the one that suits you.

1. Look for a reliable company. Donít choose one your uncle Frank developed in his garage, pick one with a reliable track record. This includes ease of maintenance or repair.
2. Pick one that filters to the level you desire.
3. Pick one thatís easy to obtain filters for or clean.
4. Look for one you can be comfortable using. Some have different pumping actions that are easier to use.

For elements, there are 2 basic types:

1. Flexible: The flexible element is used in the Pur Hiker and Guide models and is made of a woven glass. It is not cleanable but is not as susceptible to failure in freezing temperatures.
2. Fixed: The most common is a ceramic filter, but there are pure carbon ones on the market as well. The carbon ones are nice, but tend to plug up easier and are almost impossible to clean. The ceramic ones are easy to clean, but cannot be used in freezing temperatures.

There are also combination filters that combine a filter element with either a polishing medium or a disinfecting medium. The polishing medium is usually a carbon core, which will reduce taste issues and provide a ďcatch-allĒ safeguard should the main element start to bleed through, but it does not disinfect. I highly recommend them if you have the option. The water ďpurifiersĒ have a disinfecting medium attached to the filtering element that is usually triodide or pentaiodide resin (more effective), but these are more expensive and cannot be cleaned.

I have done some testing on the filters I own, which are the Pur Hiker (13.5 oz), MSR Miniworks (same main filter as the Waterworks), MSR Waterworks (17.2 oz, same main filter as the Miniworks, but with an added second stage), and the Guide (10.8 oz, which needs a new element). The MSR Waterworks will remove more than the Hiker or Miniworks, but it isnít really necessary to filter to that degree. Some people have mentioned using a sock, T-shirt, or bandana to filter the water, so I tested those as well. The T-shirt and bandana came in tied at 2.5% efficiency and the sock came in at 1.3% efficiency, so I wouldnít even waste my time with them. By comparison, the Hiker was 89.2% efficient, the Miniworks was 87.3%, and the Waterworks was 97.7%. I performed all these tests filtering 1 liter of the same base lake water (like youíd find on the trail) in my lab.

But, now that most of the pathogens are removed, you still need to address the rest, which can still mess you up. This is where the second stage of the water purification comes into play, and itís called disinfection, which is the killing of pathogenic (disease causing) organisms.

Lawn Sale
04-23-2006, 02:50 AM
Obtaining potable (safe) water while on the trail, Part 2

Up to now itís been fairly simple: filter the water. Now there are some real choices to be made, like which disinfectant or type to use. There are a myriad of choices here, but Iíll only touch one the ones readily available. The chemical disinfectants include chlorine bleach, chlorine dioxide, iodine, and the MIOX system. Mechanical disinfectants include Ultra-violet radiation (Steri-pen) and boiling. I am purposefully omitting using chloramination, hydrogen peroxide, potassium permanganate, ozonation, and bromination as disinfectants because they are not applicable to the hiking world as of yet.

With all disinfectants there are water quality issues to be taken into account. These I have listed in order:

1. Water clarity. The filters really come into play here, as the clearer the water is, the more effective the disinfectant will be. Basically, if you filter, then all of them will work about the same, if not, then another host of problems arise.
2. CT. Referred to as C and T (just the letters), this stands for Concentration x Time, which is the disinfectant dosage multiplied by the amount of time the dosage is in contact with the water. For example, a CT of 100 could be achieved by having a dose of 4 and a time of 25. Or, it could be a dose of 2 and a time of 50. Each disinfectant has a CT table associated with it, based on different temperatures and pHís, but Iíll save you the time and headache by using a standard water quality we see while hiking.
a. Dosage. How much disinfectant you put into the water. I am assuming disinfecting one liter of water, just to keep things as constant as possible. Obviously the more you put in, the faster the disinfectant will work. But, youíll also notice it more in the taste category.
b. Contact time. The amount of time the disinfectant is in contact with the water. This is how long you wait before you drink the water you added the disinfectant to.
3. Type of disinfectant. I have listed them below, with their attributes. Some you will need to add more of the chemical, some youíll need to add less. Each has a different cost, ease of use, taste, and potential side effect associated with it, so youíll need to weigh these accordingly.

Here I have listed the disinfectant types, along with some tidbits. I am assuming a pH range of 6 to 8 (most lakes and rivers in New England are around 6), and a water temperature of 8įC to 10įC (45įF to 50įF). Colder water and very low or high pH values have a negative effect on the disinfectants and normal pH and higher temperatures allow the disinfectants to work better.

1. Chlorine bleach, aka Sodium Hypochlorite. In stores you can get it as a 5% solution, but if you look in the pool section you can get HTH, or High Test Hypochlorite (powdered calcium hypochlorite), which can be mixed much stronger.
a. Pros: Cheap, easily obtainable, requires only a very small amount (+/- 2 drops per liter), very effective against viruses and bacteria (+/- 6 to 30 minutes).
b. Cons: Produces harmful byproducts in turbid (less then clean) water, degrades quickly over time, easy to taste in the water, easily influenced by materials in the water (tannins, dirt, organics, etc).
c. Giardia and Crypto: Not effective against Crypto at all. Takes 70 to 100 minutes to inactivate Giardia.

2. Chlorine Dioxide, aka Aqua-Mira (USA) or Pristine (Canada).
a. Pros: Lightweight (2.7 ounces for both containers), stable when kept separated, very effective against viruses and bacteria (+/- 15 to 20 minutes), does not produce harmful byproducts, reduces or eliminates taste and odor issues.
b. Cons: Unstable when mixed (must be used immediately), limited life span on base reagents (so I recommend buying a new one for $12 each year).
c. Giardia and Crypto: Takes 100 to 120 minutes to inactivate Crypto. Takes 15 to 23 minutes to inactivate Giardia.

3. Iodine. Stock solutions can be made and bought, but the primary form Iím referring to is the iodine tablet.
a. Pros: Easily obtainable, easy to use, forms few harmful compounds, very effective against viruses and bacteria (+/- 20 to 30 minutes), stable, does not form harmful byproducts.
b. Cons: Taste issues, much slower reaction at lower temperatures, ingestion of concentrated or long term doses may be harmful.
c. Giardia and Crypto: Not effective against Crypto. Takes 50 to 60 minutes to inactivate Giardia.

4. MIOX, aka Mixed Oxidants. Add salt and water to a little pen style unit, hit the button, and presto, instant Miox. Electricity is passed across titanium coated electrodes in a brine solution to create concentrated hypochlorous acid, the main disinfection component of chlorine, and other chlorine compounds.
a. Pros: Very effective against viruses and bacteria (+/- 5 to 20 minutes), lightweight, no taste issues, produces less harmful byproducts than chlorine, claims filtering the water is not necessary.
b. Cons: Costly ($130), dependent on batteries and salt, all of the mixed oxidant chlor-oxygen compounds formed have not been addressed for side effects (the MIOX website even addresses this).
c. Giardia and Crypto: Takes 220 to 240 minutes to inactivate Crypto. Takes 15 to 40 minutes to inactivate Giardia.

5. Ultra-Violet (UV) aka Steri-Pen. A light emitted at 254 nanometers through a quartz sleeve for a specific amount of time. The light disrupts the DNA sequence of the organism so it cannot reproduce and thus dies off.
a. Pros: Forms no harmful byproducts, water quality from a taste and sight perspective remains unchanged, fast rate (in about a minute).
b. Cons: Certain compounds in the water can absorb the light, making it less effective; dependent on batteries and the unit not breaking down, turbid water can prevent organism destruction by hiding in the shade of the particles, costly ($150), limited life span on the bulb, not sure if it can be replaced (but the bulb life span on other UV systems is very high), does not inactivate certain virus strains.
c. Giardia and Crypto: Effective against Giardia and Crypto.

6. Boiling. Bringing the water to a boil below 12,000 feet in elevation.
a. Pros: Complete destruction of the organisms, can be used all year, creates no harmful byproducts.
b. Cons: Requires bringing excess fuel and a stove, time required allowing water to cool.
c. Giardia and Crypto: Very effective as neither one can sustain the high temperatures of the boiling process. Both die off just under 190įF.

People ask what I use all the time since I have been treating all forms of water over the last 14 years. I use a MSR Waterworks filter with a ceramic and carbon element, and disinfect with Aqua-Mira, as I donít like the chlorine taste. Itís simple, effective, inexpensive, and easy to use. But, this is the combination I chose based on what I wanted, so donít feel the need to follow in my footsteps unless you want to, other combinations work just fine.

In summation, obtaining reliable potable water requires a two-stage process or a lot of time. If you choose not to filter, then be sure you pick a disinfectant and wait the appropriate time for it to work. If you do filter, then make sure you disinfect so you complete the process. Sure, you can not filter or disinfect and get away with it, most of the time. But, you can also not wear a seat belt on the highway and hope you never get into an accident, itís your choice. Personally I wear my seat belt and purify my water, because ďstuffĒ happens.

I think itís irresponsible to recommend people not bother to filter and/or disinfect their water when they really have no idea of the water quality in any area. The fact is most of the pathogenic organisms come from the south bound end of a north bound animal. In other words, how do you know an animal didnít just go #2 upstream of you. For that matter, how do you know one didnít go a week ago, or there isnít one dead in the water source you got your water from. Fish, frogs, waterfowl, and other amphibious creatures routinely ďgoĒ in surface waters, so do you really want to drink it without some form of treatment? The simple answer is that you donít. All these studies on this stream or that lake are also only a snapshot in time, they are no guarantee the water at that moment is clean.

bruno
04-23-2006, 08:54 AM
wow! i didn't read it all, but dude! you really get into it here! :) :)

absolutely NOTHIN' left to say! :eek: :)

MattC
04-23-2006, 09:04 AM
You mention iodine having a longer reaction time at lower temperatures. Any opinion on how temps affect the other chemicals?

Matt

Davehiker
04-23-2006, 09:05 AM
Lawn Sale -

Thanks for the reminder/update. I've been using a ceramic filter without further disinfection. I'm just lucky, I guess!

What CT of chlorine is needed to kill viruses in filtered water? When you state 1-2 drops / litre, are you refering to 5.25% bleach? What PPM are you looking for?

Thanks

kmorgan
04-23-2006, 09:18 AM
Excellent article. Much more complete than enything I can recall reading either in so-called "handbooks" or magazine articles on the topic.

I've always used the Pur "hiker" filter, but have never bothered with disinfecting under the misconception that after filtering it was unnecessary. Now that I know better I will count myself as lucky and start carrying a disinfecting agent.

Thanks for the great post(s).

Kevin

jrichard
04-23-2006, 09:20 AM
I'm one of those who thinks this water safety thing is overhyped - that cleanliness is a more important prevention. More on this below. From the 70s to the mid 90s we drank most WMNF water without treatment. We did boil water from questionable sources - Kinsman pond, Unknown Pond.

None of us got sick from this. But someone with a weaker immune system may have. Now I bring a filter when hike with a group. I'm willing to take a chance on my own intake, but not on others.

But, more importantly in my opinion, I also bring liquid hand sanitizer. After every bathroom stop and before meals, this stuff gets used.

It's my understanding that, although giardia is one of the more frequent waterborne illnesses, the chance of getting giardia from person-to-person or object-to-person contact is greater than that from water. How many people do you know who wash their hands after handling children? Diapers? Toys at a daycare center?

mediclimber
04-23-2006, 09:36 AM
Thank you for a very infomative set of posts. Guess I gotta get some Aqua Mira too.

onestep
04-23-2006, 09:37 AM
I'm one of those who thinks this water safety thing is overhyped - that cleanliness is a more important prevention.

Yesterday whle 'whackin down Hutchins I stopped for a long cool drink of untreated water... :eek:

Onestep

paul ron
04-23-2006, 12:13 PM
Great article, you've covered just about everything.

On the issue concerning immunity. You say one can't become imune? Why don't Mexicans in Mexico get sick from the same water you and I would almost drop dead from, they drink the stuff like it's water right out of the puddle in their backyards? Are they immune?

Chemical contaminants have not been addressed. I understand carbon can remove some taste issues but will they remove the lead and heavy metals of say a mining source out west, or the chemical run off of factories in Pa?

I've been backpacking the Northeast nearly all my life and never filtered once in 40 years, yet I have never gotten sick. Is that because I am a good canididate to be Mexican or I have been lucky?

Can you also explain why drinking water at the source that eventually makes it to my tap here in NYC would require anymore filtering if the only treatment NYC does is Chlorine? They also ensure 99.99% purity in all the reports I recieve from the DEP. Are they scamming me? Should that water still be filtered before it gets to my tap? Is Chlorine a sub standard method, not able to kill off all the pathogens? If so why would NYC use it and still guarentee that level of pathogenic purity.

I wish someone would talk about proper use of the filter from an infection control standpoint because the chances of cross contamination is so great with improper use, it almost as if no filter was used at all.

Do you work for the DEP, maybe a filter manufacturer or are involved in sales? Do you have any credentials to be so mater of fact about this subject?

Thanks for the great info, it raises alot of questions as well as clear up some myths.

DougPaul
04-23-2006, 12:19 PM
Lawnsale--nice discussion--thanks.

There is also a good section on water disinfection in "Medicine for Mountaineering", James A Wilkerson, ed.

Freedom of the Hills also has a short section on the topic.

One dual approach is to filter the big stuff (bacteria, parasites, and parasitic cysts) and then use iodine (.5-1 mg/l) to destroy anything left (viruses etc). This concentration of iodine is tasteless. (Concentrations of 8 mg/l are required only for for killing parasitic cysts.) (Info from Wilkerson.)

A hiking magazine article suggested the use of 2--8 mg/l of iodine for purification. 2 mg/l for cleaner, warmer water with longer contact times, 4 mg/l for medium, and 8 mg/l for dirtier, colder water and shorter contact times.

Iodine was tested on Cambridge (MA) city raw sewage...

My favorite form of iodine delivery is USP tincture of iodine because it is readily available and stable. USP tincture of iodine is 2% diatomic iodine (the active component) plus 2.4% sodium iodide in 50% ethanol. .5 cc of tincture in 1 liter of water gives 1 mg/l. (Also from Wilkerson.) This approach has the disadvantage that it contains the useless sodium iodide.

Doug

Rick
04-23-2006, 12:24 PM
I did the iodine tablet route for a few years, but after a night at Moose Pond in the 'daks and drinking stagnant insect/micro-organism ladened water, I decided on a filter. I used a First Need for about 4 years then switched to a Pur Scout for about another 4 years and have had my MSR Miniworks now for about 8 years and have had no issues.

I do keep a backup bottle of tincture of iodine in 10 essentials kit (I keep it in a dark brown glass eyedropper style bottle that you can get at a drugstore for $1.)
My filter weighs about a pound and along with my deodorant :D it really makes me feel secure in the puckerbrush.

Lawn Sale
04-23-2006, 05:14 PM
Thanks for the replies all. I'll try to address what I can.

mcorsar, the other chemicals also have a reduced efficiency at lower temperatures. Basically everything in the water slows down, so the reactions take longer.

Davehiker, yes, for the 1 to 2 drops per liter I was referring to the 5.25% bleach. You are looking for about a 2 ppm (parts per million) free chlorine residual on the water. An easy way to test this is to get some free chlorine test strips from any of the manufacturers (Cole Parmer, Hach, VWR, etc), they run about $15 for a 50 pack. I did some actual testing the lab and used 2 drops of chlorine per liter of water filtered through the Hiker to come up with about 2 PPM of residual. The CT is relatively low to kill just the viruses, in the range of 3 to 10.

jrichard, you're right about the cleanliness issue. While I do not have the stats on it, I have heard it's relatively high. We do not go into detail in the water world on it as it's not our area of expertise.

paul ron, everyone is different and nothing is exact, but it's highly unlikely you can become immune. However, you can adapt, which is what I think has happened, to some degree, with the people south of the border. They are more tolerant to the waterborne diseases so it takes more to get them sick, but they are certainly not immune. This is true of almost any regional people, like the Eskimo's tolerance for cold or the people at the equator's tolerance for heat. People can adapt, but what we're taking about is drinking potentially tainted water, which is a hit or miss proposition.

The carbon will remove only traces of lead and other heavy metals from the water. The ones used to treat hazardous water are designed differently, but are made up of similar material.

As to not getting sick after 40 years, maybe a little of both! :) Your immune system may be better or maybe you are drinking more selectively and guessing correctly. I'm not saying every water source out there is contaminated, as they certainly aren't, I'm just saying that since we don't know, it's better in my mind to err on the side of caution.

NYC has an extensive program for testing for Crypto and Giardia, as set forth by the EPA. They are below the threshold for requiring further removal, so they don't need to filter - yet. Many systems across the US are like this, but the regulations are tightening on an annual basis. Some local water utilities will have to install filters or change disinfectants in the near future to maintain compliance. Upon looking into NYC further, they were granted a waiver for filtration in 1993, so they don't have to filter, but they do have to maintain a rigorous watershed protection program to keep the water entering the system as clean as possible. The 99.99% purity report they send you should be correct, but since they have small amounts of crypto and giardia as determined through the monitoring, they can meet the current requirements. If the report is not factual someone is going to jail as it's a federal offense to falsify the report. Check this (http://www4.nationalacademies.org/news.nsf/isbn/0309067774?OpenDocument) out for more info.

You are right about the proper use of the filter to avoid cross contamination. Many people overlook this, but the newer ones out there are pretty easy to use properly to avoid this cross contamination.

I have no problem questioning someone's credentials in an area, but I usually don't "toot my own horn". I do not work for the DEP (they asked me to come work for them, but I didn't want to take the pay cut) nor am I affiliated with any of the filter or chemical manufacturers.

My credentials:
I spent 10 years working for an Environmental Engineering company specializing in all forms of water treatment. This includes all potable water, waste water, and hazardous water remediation. I have worked at too many sites to list, managing some, providing technical support for others, and even redesigning ones that needed an upgrade. I left 4 years ago to spend more time with my wife (I'm now divorced) and worked for a large city's water district for 4 months until something closer to home came open. For the last 3.75 years I have been at one of the most advanced water treatment systems in the state, putting out 2 million gallons a day of city water that is on par with the best bottled water money can buy.

I am currently the highest certified operator in the state of Maine and hold the following licenses and certifications:
Maine Class IV Water Treatment (highest)
Maine Class IV Water Distribution (highest)
Maine Grade 5 Biological Wastewater (highest)
Maine Grade 1 Physical-Chemical Wastewater (highest)
New England Laboratory Class II (highest)
New England Collection Systems Class IV (highest)
OSHA 40 Hour Hazardous Waste Operations and Emergency Response
OSHA 24 Hour First Responder (second level)

I have many other awards as well, but they're just in-house ones. They don't count here so I left them out.

Clown
04-23-2006, 05:21 PM
Is crypto something the average person should worry about when drinking water? Or just someone with a very weak immune system.

paul ron
04-23-2006, 05:48 PM
Thank you for your insights. I am very impressed with your qualifications adn can see why your article is so in depth.

As for proper use, I am talking about how people handle their filters in the field. They rinse off their hands in the potentially contaminated water, then filter water into a bottle which is handled with the same contaminated hands. Putting your bottles down by a contaminated source will also cause problems. After using the filter all the hoses are handled causing contamination to the user and they are stored in the same bag where contaminated water comes in contact with both the clean hoses and filter body. If a bandana was used as a pre filter in the stream and handled by the user it is a source of contamination again as well as posably reused or stored with clean items, which in turn is now a source of delayed contamination in a new location. Not many people are aware of their infection control habbits.

Again thanks for the info, I found it enlightening adn have already passed it along to some friends.

DougPaul
04-23-2006, 06:11 PM
Can you also explain why drinking water at the source that eventually makes it to my tap here in NYC would require anymore filtering if the only treatment NYC does is Chlorine? They also ensure 99.99% purity in all the reports I recieve from the DEP. Are they scamming me? Should that water still be filtered before it gets to my tap? Is Chlorine a sub standard method, not able to kill off all the pathogens? If so why would NYC use it and still guarentee that level of pathogenic purity.
Purification requries a certain concentration of free chlorine in the water. Organics in the water can absorb chlorine and make it unavailable for purification. A municpal plant can measure this concentration and adjust the amount added to produce the appropriate concentration. Not practical in the field. (Info from Wilkerson.)

Doug

Aviarome
04-23-2006, 07:04 PM
I have always filtered/disinfected backcountry water and will continue to do so to avoid any chance of infection, and though I do not disagree with Lawn Sale's opinions, I would like to point out that there has not been wide conclusive evidence that backcountry water is heavily contaminated with coliform bacteria, giardia, cryptosporidia, etc. There is always a chance, but there has not been a good study that assessed the risk for contracting these infections. In fact, a meta-analysis of results did not show a strong correlation between giardiasis and drinking backcountry water. Other sources to check out are

Wilderness Environ Medicine. 2004 Winter;15(40):235-7.
Winderness Environ Medicine. 2004 Winter;15(40):238-44.

However, I am not sure of any new studies since 2005, and if anyone else has found evidence to the contrary, then please let me know.

aviarome

Pete_Hickey
04-23-2006, 09:59 PM
.... From the 70s to the mid 90s we drank most WMNF water without treatment. And we also ate raw eggs.. in eggnog, ceasar salad, eating raw cookie dough, etc. You can't do that any more.. I gues it's those new chickens.

griffin
04-23-2006, 10:20 PM
And we also ate raw eggs.. in eggnog, ceasar salad, eating raw cookie dough, etc. You can't do that any more...

Some of us still do ;)

But then I'm not worried about hikers pooping or critters decomposing in my fridge or near my egg basket.

danno
04-23-2006, 11:52 PM
Excellent information Lawn_Sale (and others), Thanks!. I have only filtered water over the last 15 or so years, and now know I have been lucky thus far. A timely post as I'm due for a new filter.

Is there a graph/scale that, after filtering, discusses amount of time required to kill crypto/giardia with Aqua-Mira based on water tempurature? (there's still a lot of cold water out there).

Lawn Sale
04-24-2006, 12:45 AM
Clown, I would say both. While someone with a deficient immune system will obviously be more at risk, healthy people can still be affected. One thing I'd like to note here, and you just reminded me about it, is that public water supplies, and the rules in general, are based towards the best possible water for 99% of the population, so they err on the side of caution, as they should. You and I hiking are only concerned about one person, ourselves (or a family/group if you're together), so we may choose to take more risks, and we have the leeway to do just that. Water suppliers don't have that option.

paul ron, I agree with you. The filter I was thinking about when I mentioned that was the Miniworks/Waterworks that attach directly to the top of a Nalgene. With the cover in place, the is virtually no cross contamination possible, unless its from your hands.

DougPaul, the test strips I mentioned are a good way to check for the free chlorine residual in the water. No matter what the demand, the strips will tell you what the residual is, so you can determine if you need to add more chlorine or not. Unfortunately these only work for chlorine at present. MIOX uses these same strips as part of their "package", but they have their ownlabels on them. If you're using chlorine, it's a good way to keep everything in check so you don't add too much or too little.

Aviarome, you are correct. There is no evidence to say heavy contamination exists in all areas, but there are select sources, hence the need for prudence, at least in my eyes.

Something else I would like to add is that a lot of the information gathered is fact and some is my personal opinion. The facts speak for themselves, the size of the organisms, the possible presence in water supplies, and the filters. But, those that are my opinions should be taken as such, my opinions. I'm not trying to get everyone to filter their water, I just want everyone to have the facts as they are so they can make their own decisions. It honestly does not matter to me if people filter/disinfect, they are free to do as they choose, and I won't think less of someone who does or does not. I just didn't want people to assume this is my way of trying to get people to do something over something else.

sardog1
04-24-2006, 09:10 AM
[CENTER]5. Ultra-Violet (UV) aka Steri-Pen. A light emitted at 254 nanometers through a quartz sleeve for a specific amount of time. The light disrupts the DNA sequence of the organism so it cannot reproduce and thus dies off.
a. Pros: Forms no harmful byproducts, water quality from a taste and sight perspective remains unchanged, fast rate (in about a minute).
b. Cons: Certain compounds in the water can absorb the light, making it less effective; dependent on batteries and the unit not breaking down, turbid water can prevent organism destruction by hiding in the shade of the particles, costly ($150), limited life span on the bulb, not sure if it can be replaced (but the bulb life span on other UV systems is very high), does not inactivate certain virus strains.
c. Giardia and Crypto: Effective against Giardia and Crypto.

All in all, a most excellent article and a real service -- KUDOS!

FYI, a pre-filter is available from the SteriPEN maker for $9.95 that removes light-blocking particles before the light is applied. The bulb can be replaced, but the programmed life span (about 4.5 years of thrice-daily use) far exceeds the likely use by any but the most hardcore hiker or traveller. (The actual tested life span of the bulb is about double that.) You can read lots more details at SteriPEN FAQ (http://www.steripen.com/faq.html).

I know several users, one of whom uses his regularly in the Whites in the winter. He keeps the batteries warm and pulls them out only when needed to treat water. Note the manufacturer's recommendation to use NiMH batteries, NOT lithium or alkaline, in cold weather.

Pete_Hickey
04-24-2006, 10:10 AM
....raw wggs...
But then I'm not worried about hikers pooping or critters decomposing in my fridge or near my egg basket.
'y point was that we've developed a fear of germs. Things that we used to do, are no longer acceptable. Look at all the disinfectant soap available these days. What did we do before? You'll get salmonela if your eggs aren't cooked enough.... Ever get runny yellow eggs at MacDo's.

How much of this water filter stuff is because the water is really worse, and how much because you're just more 'aware'?

If you have a 50-50 chance of getting giardia, do you treat water?
What if a 1% chance. How about 0.001% How about 0.00001%
Yes, there is a CHANCE there is something in the water, but what is
that chance.

What about the 'Dear Abbey Syndrome": "If it saves one life it's worth it." "It's better to be safe than sorry."

When questioned about my aluminium foil hat, I'll tell you it's to protect me from both the alien and government mind rays. You may think I'm crazy, but IF THEY EVER INVENT the mind rays, who'll be laughing then? It's better to be safe than sorry.

lumberzac
04-24-2006, 10:26 AM
How much of this water filter stuff is because the water is really worse, and how much because you're just more 'aware'?


Very good point, but doesn't it also stand to reason that there are far more people in the backcountry than there used to be which in turn would increase the chance that water could become contaminated? Iím not sure what the answer is, but I plan to keep on treating my water as I have in the past.

griffin
04-24-2006, 11:42 AM
'y point was that we've developed a fear of germs. Things that we used to do, are no longer acceptable. ...

How much of this water filter stuff is because the water is really worse, and how much because you're just more 'aware'?


I did understand your point. Mine was that there are usage issues that, imo, make caution about one's water source seem less like over-reactive fear of germs. (and I"m sorry if my attempt at humor came of as a swipe at you, it wasn't meant that way) - especially since most places we get water in the woods see a fair amount of human traffic.

I do wish there were more solid data on water quality in the area, and yes, if that data were available and the risk was proven small enough, I'd consider skipping the filtration. As it is, 16oz added to the pack seem a reasonable enough precaution against what could be weeks of gastrointestinal misery.
We all have our own risk tolerance, I guess.

danno
04-24-2006, 03:15 PM
I know several users, one of whom uses his regularly in the Whites in the winter. He keeps the batteries warm and pulls them out only when needed to treat water. Note the manufacturer's recommendation to use NiMH batteries, NOT lithium or alkaline, in cold weather.

A note on Cold Weather Use from the SteriPEN user manual (from their site):

If SteriPENô is at a temperature below 32įF/0įC it should not be used. Bring SteriPENô up to a temperature above 32įF/0įC before using.

This is in addition to cold weather battery performance. The SteriPEN itself needs to be above 32 degrees to work properly.

sardog1
04-24-2006, 03:42 PM
Thanks for the correction -- I now recall that he keeps the whole unit inside his clothing when he needs to use it.

darren
04-24-2006, 04:27 PM
As for proper use, I am talking about how people handle their filters in the field. They rinse off their hands in the potentially contaminated water, then filter water into a bottle which is handled with the same contaminated hands.... After using the filter all the hoses are handled causing contamination to the user and they are stored in the same bag where contaminated water comes in contact with both the clean hoses and filter body ... Not many people are aware of their infection control habbits.



A very important point. I always store the filter's outlet side hose in a zip lock bag which is kept seperate from the rest of the filter. It is a good habit to get in.

- darren

DougPaul
04-24-2006, 05:26 PM
After using the filter all the hoses are handled causing contamination to the user and they are stored in the same bag where contaminated water comes in contact with both the clean hoses and filter body.
One of the nice things about the MSR Mini-Works and Works filters is that they screw directly onto a Nalgene bottle (or Nalgene fitting on a bladder) and have a cover for the clean end of the filter. (No clean hose required if you attach the filter directly to the bottle/bladder.) Makes it a bit easier to avoid contaminating the clean portions of the system.

Doug

jrichard
04-24-2006, 10:01 PM
Speaking of contamination from rinsing hands and then touching hoses, bottle rim, etc... This is probably a small amount of water/contamination.

Considering the amount of water I end up swallowing when rolling a kayak, I wonder if it is worth bringing a filter on kayaking trips! Even when canoeing, there's splashing, touching the paddles, even purposely dunking my hands!

Woody
04-24-2006, 10:37 PM
I usually use my MSR mini-works filter although I have drank water directly from streams in the Whites when I felt the chance of comtamination was low. I've been lucky and have never gotten sick.

DougPaul
04-25-2006, 12:07 AM
Considering the amount of water I end up swallowing when rolling a kayak, I wonder if it is worth bringing a filter on kayaking trips! Even when canoeing, there's splashing, touching the paddles, even purposely dunking my hands!
According to http://lomaprieta.sierraclub.org/pcs/articles/giardia_2003.pdf studies have shown that one has to ingest 10 or more cysts to have a reasonable probability of contracting giardia. So pull out when you reach 9... :)

Doug

Lawn Sale
04-25-2006, 11:27 PM
While I work in the water industry, I am by no means an expert on Crypto or Giardia, so I did some research on the issue to become more familiar with the nuances of each organism. Actually I devoted quite a number of hours to this research, but it's always good to expand ones knowledge base, and you guys are worth it. I found some interesting items, some of which I knew, but some of which was unknown to me. The CDC and EPA have some information on their websites, but a significant amount of information came from Britain, where extensive research was done to combat the growing problems over there.

This is not designed to be a scare tactic, but I found some interesting tidbits of information. I also found conflicting reports on the adaptability to Crypto, where some publications say you can build up a resistance to it and some say you cannot. The information I have at work (c.1995) says you cannot, but itís a topic in constant evolutionary flux, so I donít know which one is correct.

Cryptosporidium:

Cure: Cryptosporidiosis has no cure so there are no medicines that can be prescribed.

Length of illness: The positive side is that it will usually run its course in 3 to 4 weeks, but the person can still be infectious for another 6 to 8 weeks.

Infection rate: Higher infection rates are associated with younger age children (less than 5 years old), warm, wet weather, and overcrowding near sources.

Infection requirements: Normal infections are thought to require 100 oocysts, but as few as 2 have shown to be infectious in controlled tests on certain individuals. Severity and course of the illness are determined by host immunocompetence (I also learned a new word!).

Symptoms: Symptoms include diarrhea, abdominal cramps, malabsorption, and weight loss, and they show up between 2 and 14 days after infection, with an average of 7 days. Symptoms resemble food poisoning, so it often goes unchecked. It is usually a severely debilitating illness and may cause death.

Survivability in the wild: They can survive for months in soil under cool dark conditions, for up to a year in low-turbidity water, but will not survive the freezing process. A few sites theorize that 87% to 93% of the surface waters in the country are contaminated with Crypto, and 85% of all those tested have some level of Crypto in them.

History: It was first recognized in 1907, but extensive work on it has only progressed during the past 20 years. Crypto has become recognized as one of the most common causes of waterborne disease in humans in the US. The parasite is found in every region of the United States and throughout the world. The first documented major outbreak was in Texas in 1984 when 2006 people were infected through sewage contaminated well water and a failure to check the disinfection injection system. The most major incident happened in 1993 in Milwaukee when over 400,000 people became ill and more than 100 died after drinking lake water that had not been adequately treated. I have no idea as to the immunodeficiency of the fatalities, so I do not know the status of the deceased before the outbreak.


Giardia:

Cure: Giardiasis has a cure, but left unmedicated it can last for years with sporadic outbreaks.

Length of illness: Documented cases of the illness lasting up to 4 years have been recorded, with one over 30 years. Unlike Crypto, Giardiasis is not a disease that may be fatal, although if left untreated the victim may suffer for an extended period of time, seemingly getting better and then having relapses on occasion.

Infection rate: The runoff from rainfall can cause an increase in cysts in streams, rivers, lakes, and reservoirs. It has been reported that there is an increase in Giardia infections during and after heavy rainfall. One or two cysts are unlikely to cause an infection unless the individualís immune system is severely compromised, as may be the case with the very young, the elderly, or AIDS sufferers. As with most infective agents there is usually a so-called ďinfective doseĒ, which depends on the physical condition of the person who is infected and the state of their immune system, so the size of the infective dose will vary.

Infection requirements: Cases have shown as few as 10 cysts can infect a person, but a group of 40 received a dose of 1,000,000 (yes, one million, Iíd hate to be in that group!), with only 21 showing symptoms. The severity of the illness can vary considerably with host immunocompetence and only about a quarter of the people infected show symptoms of the illness, but can still infect others.

Symptoms: It has symptoms that are similar to food poisoning as well, to include acute diarrhea, which is often explosive (Ok, this should prompt people to rethink water treatment strategies!), abdominal cramps, bloating and excessive flatulence. The incubation period can be anything from 1 to 75 days with a median of 7 to 10 days. In an AWWA study, subjects who received 10 cysts found the median to be 9.1 days.

Survivability in the wild: Studies of the survival of Giardia cysts in the environment show they can survive for months in fresh water. Not all cysts are viable though, which means they are able to hatch and start the infectious cycle.

History: Giardia cysts are widely found in lakes and rivers especially where there is wildlife that uses these water sources. Concentrations as high as 240 per liter in surface waters were found, and there is evidence that cysts can also contaminate groundwater. Outbreaks are more common in the US, possibly because of more infected animals in the wilderness, which are popular areas for hiking and camping. In the period of 1971 to 1985 18% of all outbreaks of waterborne diseases were caused by Giardia, and it's speculated that number is much higher today.


As I mentioned before, Iím not trying to be an alarmist. The purpose here was to educate people on the possibilities of infection from waterborne diseases so they can make their own decisions on whether or not to treat the water. Thatís not to say all sources are contaminated, as Iím sure they arenít. These two organisms are the most concentrated upon because of their relatively new and increasing status, their debilitating characteristics, and their resistance to destruction. I have friends that choose not to filter, their rationale is that by the time they contract something, theyíre at work anyway, so it doesnít matter.

I always recommend people hike their own hike and this is no different. But, hopefully the information I have posted will shed some light on truths & myths, and provide a little information from which people can make their own educated decisions.

.

Kevin Rooney
04-26-2006, 12:41 AM
Thanks for a superlative thread, Lawn Sale. A gem like this makes wading thru the usual stuff worth it.

Jazzbo
04-26-2006, 07:45 AM
Great thread Lawnsale! ... I agree with Kevin .... I'm going to try printing this one out. If I run low and need to obtain water on the trail and I don't have my filter I try to be selective and opt for the little seepy type springs just below tree line recieving from rocky mossy spruce areas with no trails passing by overhead. Even with the filter I try to be selective about picking my water source. The lower the source the more chance of getting poop byproducts. I like the MSR Miniworks for its ease of use as it screws to the top of a std liter water bottle and eliminates a juggling act of suspending multiple hoses on uneven terrain of rocky brooks. I'm going to take Lawnsale's advice and obtain Aqua Mira or other chem treatment.

Greg
04-27-2006, 08:11 PM
Good info and good coverage, Lawnsale. It's always better to be safe, I think. Why court giardia if you don't need to.
Another class IV systems operator from the State O' Maine. :eek:

jrichard
04-27-2006, 08:59 PM
I too think Lawn Sale's documentation is to be applauded.

I was speaking with someone who works in medical dialysis. She says that one of their patients ruined most of their kidney function as a result of drinking water from a stream during a honeymoon hiking trip. It's a second hand story, and there's no easy way for me to find out if it was a biological or chemical agent that caused the destruction, but it does make me pause when deciding if I want to use the aqua mira.

Although for me, it's not so much the mountain streams that I worry about, it's the chemical runoff into the lake and streams. I drink that stuff on canoe/kayak trips.

Aviarome
04-27-2006, 10:00 PM
It sounds like that person had hemolytic uremic syndrome (HUS), which is often caused by a strain of E. coli. Obviously, E. coli is one of the important coliform bacteria that people worry about in contaminated water. Although, this is a very rare infection for backpackers drinking cleaner waters. It's more common to acquire this through contaminated foods and water heavily contaminated with feces.

Chemicals may also have caused the kidney problems, but it sounds like a case of HUS.

aviarome

Quietman
04-27-2006, 10:56 PM
If I run low and need to obtain water on the trail and I don't have my filter I try to be selective and opt for the little seepy type springs just below tree line recieving from rocky mossy spruce areas with no trails passing by overhead.

This was my approach as well. Was hiking on Moosilaukee a couple of years ago with my 70 year old father, which required an overnight on the Benton trail about 2.5 miles in. Ran low on H2O but found a little seep spring far from the trail for a refill. Filled up the 1/2 gallon bag, started to walk back to our camp site and was temped to drink straight from the bag, but just 5 feet above the spring I stepped in a very large pile of moose droppings. I was very glad I had my filter in my pack back at the camp site. False security? Who knows. I know that having the filter was worth the weight and the cost.

Hadn't thought about it before but my miniworks filter is the most expensive piece of hiking gear that I have bought at $69.95. Even my ultralight 2 person EMS tent from the bargain basement was cheaper at $65(normally $199).

I had Giardia after drinking untreated water from a low elevation stream in my younger days. Not a fond memory!

Wanderer1
04-28-2006, 08:31 AM
Lawnsale, very imformative article. I have a question on the washing of eating ware. Do these critters die once the water dries after washing? Does the soap kill them? Is it safe to wash your dishes with untreated water or can these things rehydrate and still harm you? I had ask this question a long time ago but never got an answer. I understand your cooking pots would be safe as they are subject to heat but I was thinking of eating utensiles and bowls.
Thanks

DougPaul
04-28-2006, 11:43 AM
Does the soap kill them?
Soap is not a poison. (How many kids have survived having their mouths washed out with soap?) It is a wetting agent--it reduces surface tension.

It just makes it easier for the water and abrasion to wash the surface contaminates away.

Doug

Pete_Hickey
04-28-2006, 11:50 AM
Soap is not a poison. You never used Dr. Brommers for brushing your teeth.

"It's an acquired taste."

chipc
04-28-2006, 11:59 AM
Soap is not a poison. (How many kids have survived having their mouths washed out with soap?) It is a wetting agent--it reduces surface tension.

It just makes it easier for the water and abrasion to wash the surface contaminates away.

Doug

Not sure about soap killing giardia and other protozoa, but sodium dodecyl sulfate (the common detergent in soaps) will solubilize bacterial membranes. (i.e. killing them.) Its used in labs all of the time when purifying DNA from E. coli.

Wanderer1
04-28-2006, 12:46 PM
Let me try this again. I wasn't questioning whether soap is a poison or harmful to humans. What I really was curious about is, after you've washed/rinsed something and it has dried (Water evaporated) do all the living organisms die once dry or can they still be harmful? Do you need to wash and rinse with safe water?

Aviarome
04-28-2006, 12:49 PM
I believe many soaps now are antibacterial, and most of them contain triclofan. As far as Giardia cysts, I don't know if triclofan is effective. But, Giardia cysts are vulnerable to drying and sunlight. Another note is that there are a lot of other organisms that can survive soap use, specifically viruses. I guess, to be safe, the best thing to do is to wash your dishes/silverware in treated water.

Personally, I am a very boring eater when I backpack, and usually just eat freeze-dried foods. So, I would just boil slightly more water than I need for my meal, and then wash my silverware with the extra water. And because the freeze-dried foods can be cooked and eaten out of their own packages, no dishes to clean!

aviarome

Chip
04-28-2006, 01:28 PM
Not sure about soap killing giardia and other protozoa, but sodium dodecyl sulfate (the common detergent in soaps) will solubilize bacterial membranes. (i.e. killing them.) Its used in labs all of the time when purifying DNA from E. coli.
D'OH ! Fancy words... (http://www.hdbeat.com/media/2006/01/homer-simpson.jpg)

chipc
04-28-2006, 02:07 PM
D'OH ! Fancy words... (http://www.hdbeat.com/media/2006/01/homer-simpson.jpg)
mea culpa (sorry, might be fancy too)


Just noting that in soaps the common detergent is sodium dodecyl sulfate (aka SDS or sodium lauryl sulfate) and as noted it is a surfactant. This property helps in removing grease such as that found in Homer's donut. Bacteria (as all living cells) are surrounded by a membrane composed of fat (grease) and protein. SDS basically loosens up the bacterial membrane (i.e. solubilization) by trying to remove the fat. This will damage many bacteria. While all living cells have a fat and protein membrane; they differ in how easily they will solubilize with detergents. Animals and organisms like giardia, I would guess, are much more resistant.

Just a biologist pretending to be a biochemist for few minutes :confused:

ecc
04-28-2006, 04:16 PM
I've saved the entire thread as a pdf in my "hiking etc" folder on my computer. I know I'll be referring back to it again and again.
Thanks,
ecc

DougPaul
04-28-2006, 06:03 PM
Traditional soaps were made from animal fat and were traditionally stearate (IIRC, I'm not a chemist). Modern "soaps" are frequently detergents.

In either case the primary purpose is as a wetting agent to allow fats and oils to be dissolved in water and swept away. Any pathogens that are killed along the way are an extra bonus.

Disinfectant "soaps" have been found to be no better than plain soaps in the home. I have no idea if they are any better in the woods.

The active ingredient in hand sanitizer is a high concentration of ethanol. Certainly effective against many pathogens--it is used in hospitals as a replacement for soap and water in many situations, but I don't specifically know if it is useful against crypto and giardia. (I carry hand sanitizer hiking and use it after visiting the woods and before meals.)

Doug

sleeping bear
04-28-2006, 06:24 PM
Disinfectant "soaps" have been found to be no better than plain soaps in the home. I have no idea if they are any better in the woods.


I shy away from antibacteria soap if I'm just looking to remove dirt. They kill all bacteria, including the ones that are good for you.

DougPaul
04-29-2006, 01:00 AM
I shy away from antibacteria soap if I'm just looking to remove dirt. They kill all bacteria, including the ones that are good for you.
Routine use of such soaps also encourages the development of resistant strains of bacteria.

Doug

Pete_Hickey
04-29-2006, 07:47 AM
Routine use of such soaps also encourages the development of resistant strains of bacteria.Evolution in action.

"Whatever doesn't kill you, makes you stronger." At least for the bacteria in that case.

Lawn Sale
04-29-2006, 08:33 AM
Routine use of such soaps also encourages the development of resistant strains of bacteria.


Doug

I am curious as to how they do this. I have heard this and another statement, that waterborne organisms can build a resistance to chlorine, for years, but am not sure I'm buying it.

I am not trying to start a fight, I am just interested in the mechanics behind it, as it makes no sense to me. I equate the statement to saying a person can build a resistance to bullets or a Mack truck if they are exposed to them often enough. Or more accurately, that someone else can build a resistance to bullets if someone else gets shot.

Dead is still dead is my understanding, but Iím no biologist and donít play one on TV. When you kill something it doesn't come back to life, unless it was never dead in the first place. What affects one group of organisms cannot affect the other unless some of the originals survive, and then they would have to mutate. It's not like the organisms can transmit data back to their comradeís telling them this or that, they have no organizational link and thus cannot develop ďresistanceĒ.

What is happening is that we are the ones that are reducing our immunity to the organisms by using such destructive products. Our bodies stop producing the right kind and amount of antigens needed to combat the foreign invaders by letting the products, rather than our bodies, do the work. That is how we become more susceptible to disease, not that the organisms have developed a resistance to biocides.

.

jrichard
04-29-2006, 09:09 AM
I am curious as to how they do this. I have heard this and another statement, that waterborne organisms can build a resistance to chlorine, for years, but am not sure I'm buying it.


I'm not a biologist either, but I do know one. My layman's explanation is that it isn't the individual organisms that get a resistance. It's most like evolution in action. When/if there is a (normal) mutation that allows bacteria to become resistant, it can now reproduce more quickly because the others are no longer competing.

So using the bullets analogy, if one of us just happened to mutate to where we had hide tough enough to stop bullets, the rest of us would be dead and that individual would have a much better chance of survival/procreation. And bacteria (like fruit flies and other lab test organisms) multiply much faster than us, their evolution is quicker.

At least that's how I understand it.

Pete_Hickey
04-29-2006, 09:23 AM
I am curious as to how they do this. I have heard this and another statement, that waterborne organisms can build a resistance to chlorine, for years, but am not sure I'm buying it. I never heard Chlorine, but that could be possible as well to an extent.


I am not trying to start a fight, I am just interested in the mechanics behind it, as it makes no sense to me. I equate the statement to saying a person can build a resistance to bullets or a Mack truck if they are exposed to them often enough. No, but people can build resistance/tolerance to things that could kill them otherwise. There are degrees. Note that the term is resistant, not imune. It takes a stronger dose to kill them.


Dead is still dead is my understanding, but Iím no biologist and donít play one on TV. When you kill something it doesn't come back to life Right. When you kill them they are dead. The problem comes with the ones that are not killed. Look at the case of antibiotic resistant bacteria. The problem comes when they are ALMOST killed. Those that survive are the ones that are more tolerant. It is an evolution thing, involving generations, not an individual microbe.


What is happening is that we are the ones that are reducing our immunity .... That is how we become more susceptible to disease, not that the organisms have developed a resistance to biocides. It works both ways. Google on antibiotic resistant bacteria. You'll see that US FDA and CDC right up there on the list, so it isn't some namby-manby claiming this.

DougPaul
04-29-2006, 10:12 AM
I am curious as to how they do this. I have heard this and another statement, that waterborne organisms can build a resistance to chlorine, for years, but am not sure I'm buying it.

I am not trying to start a fight, I am just interested in the mechanics behind it, as it makes no sense to me. I equate the statement to saying a person can build a resistance to bullets or a Mack truck if they are exposed to them often enough. Or more accurately, that someone else can build a resistance to bullets if someone else gets shot.

Dead is still dead is my understanding, but Iím no biologist and donít play one on TV. When you kill something it doesn't come back to life, unless it was never dead in the first place.
Pete's comment, "evolution in action" is right on the money.

In more detail:
Three cases: (This logic applies to a wide range of stressors, eg chemicals, radiation, natural or human selection (as in pulling weeds).) I also will refer to death, but anything which reduces, slows, or stops reproduction can have similar effects.
* 1. A stressor has no effect. Simple: no effect is no effect.
* 2. The slightest trace of a stressor is absolutely lethal. Dead is dead. Not much chance to adapt...
* 3. A stressor is partially lethal (perhaps due to a low concentration or inadequate contact time). There will be some genetic variation across a population of an organism, some will be more resistant than others. The resistant ones are more likely to live, the sensitive ones are more likely to die. Over time the population will contain a higher percentage of resistant organisms. And since variation is continually introduced into the gene pool by genetic copying errors, radiation damage, mutations, etc, the population as a whole can become more and more resistant. (Most such errors, radiation damages, and mutatations are harmful or lethal to the organism, but it only takes a few "good" ones...)

Examples:
1. A human scans bins of seeds for weed seeds and removes them. But he misses some of the weed seeds that look like the desired seeds. Thus over time, the weed seeds end up looking more like the desireable seeds. (Same for manual weeding of the growing plants, exept that the weed plants end up looking like the desired plants.)
2. Selective breeding. A human selects which individual organisms get to reproduce and kills those which are considered undesirable. Radiation or chemical insults may be used to increase the rate of genetic variation. Cross-breeding may also be used in introduce desireable genetic variation.
3. Antibiotic resistance. A human takes an antibiotic for some bacterial infection but stops when he "feels better". (A classic scenario...) At this point, most but not all of the bacteria are likely to have been killed. The most susceptable bacteria have died, those that remain are the resistant ones. Now free from the antibiotic, they multiply and you now have a population of resistant bacteria when you started with a population which only contained a few resistant bacteria. (This is why you should always take the full course of an antibiotic--you want to kill all of the bacteria before the population can become resistant.) Constant use of low levels of an antibiotic (such as is frequently used in the livestock industry) can have the same effect because the low dose may only kill some of the bacteria.

It is easier to adapt to some stressors than others. If a stressor attacks a specific vital molecule, perhaps a minor change in the molecule still does the biological job, but is not attacked by the stressor. (This appears to apply to the development of resistance to a number of drugs.) Stressors like chlorine and iodine (chemical ozidizers) are probably much broader in their effect and probably harder to adapt to. But these adaptation mechanisms are very powerful and will likely achieve some degree of resistance--higher concentrations may be required to kill the organisms.

Another effect of a stressor would be to alter the species makeup of an ecosystem--the population of more susceptable organisms decreases and the population of less susceptable organisms increases.

Frequent sub-lethal doses of any stressor could have either or both effects.



What affects one group of organisms cannot affect the other unless some of the originals survive, and then they would have to mutate. It's not like the organisms can transmit data back to their comradeís telling them this or that, they have no organizational link and thus cannot develop ďresistanceĒ.
Not quite true: Some simpler (single celled etc) organisms can engage in conjugation. Two individuals (which, IIRC, can be of different species) connect and exchange gentic material. Thus a trait can cross species rather than having to be developed twice independently.


What is happening is that we are the ones that are reducing our immunity to the organisms by using such destructive products. Our bodies stop producing the right kind and amount of antigens needed to combat the foreign invaders by letting the products, rather than our bodies, do the work. That is how we become more susceptible to disease, not that the organisms have developed a resistance to biocides.
This is a separate effect. Our immune systems appear to adapt in both general and specific ways to the stressors in our environments. So growing up in clean city houses (rather than playing in the dirt and being exposed to farm animals) is suspected to be a factor in the increase in allergies (generally over-sensitive immune systems). Prior exposure to some pathogens can result in specfic immunity to that pathogen or a specific strain of that pathogen (eg childhood diseases, flu). The same probably applies to a local's tolerance of the pathogens in the local drinking water which may not be shared by an unhappy traveler.

Disclaimer: I am not a biochemist. This is just my (hopefully accurate) understanding of the topic.

Perhaps a little long-winded, but I hope this helps to answer your questions.

Doug

chipc
04-29-2006, 10:27 AM
Didn't see DougPaul's comment before posting mine. He's spot on; I just have elaborated on one area he's mentioned.



I am curious as to how they do this. I have heard this and another statement, that waterborne organisms can build a resistance to chlorine, for years, but am not sure I'm buying it.

.

I don't know about chlorine, but it is true for antibiotic resistance. Yes it is evolution in action. Here's what happens in antibiotic resistance. (My apologies for the length of this post, but this is an area I am familiar with.)

You start with an infection by particular strain of bacteria. Assume that this strain can be killed by a common antibiotic, let's say streptomycin. Before you know you are infected, that one bacterium multiplies to a large population in your body, let's say a million. During this population explosion random mutations have occurred that result in one or two bacteria being a little less sensitive to streptomycin than the original infecting bacterium.

Now you know you are infected and you start antibiotic treatment. If you take the full-course treatment with a high enough dose of streptomycin, you probably will kill off all of the bacteria. However, let's say you stop the treatment early because the symptoms go away and you feel better. You may have killed off 99.9% of the bacteria, but the ones left are the those that have the mutations that make them slightly more resistant to strep. In essence you have selected for a more resistant mutant strain.

Then what happens. Your infection relapses only this time the bacterial population starts at a higher level of resistance due to those mutations. New mutations in this population can result in a bacterium with even higher resistance. This cycle can repeat until the only bacteria left are ones that have been selected for being resistant to streptomycin.

Three general points:

1) the killing agent (antibiotic or chlorine?) does not induce resistance to the specific agent; that is, "directed mutation" does not occur. You are selecting resistant variants already in the population.

2) if you are successful in wiping out the entire population with the antibiotic (or chemical or other catastrophe) then no resistant strains will appear in the population you originally targetted.

3) while antibiotics are quite effective at killing pathogenic bacteria, they also kill off beneficial bacterial strains in us. This is one of the reasons that it is now frowned upon to prescribe antibiotics without evidence that there is a bacterial infection. Its probably a simplification, but every time we take antibiotics we wipe out our bacterial population including the beneficial ones. When they repopulate our gut, it might be with more resistant strains that do it.

DougPaul
04-29-2006, 10:50 AM
Didn't see DougPaul's comment before posting mine. He's spot on; I just have elaborated on one area he's mentioned.
Yep--after I finished the cleanup edit of mine I saw that we doubled. Both posts are consistent and complementary.

Great minds run in the same gutters... :)

Doug

DougPaul
04-29-2006, 11:03 AM
As an aside, I have worked with genetic (evolutionary) methods for solving problems on a computer. They are very powerful at solving problems and can sometimes find a solution in a case were there is no traditional (numerical) method.

The keys are random variations (mutations) and a probabalistic selection function. The probabalistic selection function gives the better "organisms" a higher probability of surviving into the next generation to reproduce.

Doug

chipc
04-29-2006, 11:28 AM
Don't mean to continue the tangent, but probably most sane people are out enjoying the day instead of looking at a blue sky through their office window.



The keys are random variations (mutations) and a probabalistic selection function. The probabalistic selection function gives the better "organisms" a higher probability of surviving into the next generation to reproduce.

Doug
Interesting approach - I have heard of some computational biologists who want to "evolve" (jargony use I know) a gene on a computer so that the protein the gene makes can have a new function. The limitation at this point is predicting what the overall effect of a mutation would be on the protein structure and how that would translate into a new activity. Until this happens, we are left with actually subjecting the DNA to random mutation and then assessing the physical properties of the protein. (Not as laborious as it sounds). Nonetheless, I think applying computational evolution to a gene is not that far off.


(I am looking for the icon with taped eyeglasses but I don't see it)

Roxi
04-29-2006, 04:41 PM
Don't mean to continue the tangent, but probably most sane people are out enjoying the day instead of looking at a blue sky through their office window.

Excellent thread ChipC, Lawn Sale, and Doug! I've enjoyed reading it and learned a lot. I'm sorry to hear that at least some of you have been looking at blue sky through glass, rather than enjoying it first hand. I was one of the lucky people to be out enjoying the day, although I make no claims as to being sane. I hope all of you get to enjoy tomorrow's forecasted warm and sunny weather. Thanks again to each of you for an informative discussion, great writing, and useful information! :)

DougPaul
04-29-2006, 07:28 PM
Don't mean to continue the tangent, but probably most sane people are out enjoying the day instead of looking at a blue sky through their office window.

Excellent thread ChipC, Lawn Sale, and Doug! I've enjoyed reading it and learned a lot. I'm sorry to hear that at least some of you have been looking at blue sky through glass, rather than enjoying it first hand. I was one of the lucky people to be out enjoying the day, although I make no claims as to being sane. I hope all of you get to enjoy tomorrow's forecasted warm and sunny weather. Thanks again to each of you for an informative discussion, great writing, and useful information! :)
I went out for a bike ride yesterday, today, and have plans for another ride tomorrow. Does that count?

Doug

Quietman
04-29-2006, 08:30 PM
I took Friday afternoon off and climbed Monadnock. As I passed Falcon Spring, I was wondering if is considered a "safe" source, considering all the use that Monadnock gets. On my way down, I had consumed all my water, but still didn't drink from the spring. It sure looked good, but I didn't want to chance it.

Anyone know?

Thanks

Kevin Rooney
04-29-2006, 09:03 PM
I can't answer your question. However, most surface springs in a public area are questionable. It might test OK for coliform today, but overnight become contaminated from any number of sources.

If it were me, I wouldn't chance drinking it except in an emergency. And now, having read Lawnsale's info, I'm even less inclined.

DougPaul
04-29-2006, 10:04 PM
The following search ttp://www.google.com/search?hl=en&q=%22Falcon+Spring%22+%22Mt+Monadnock%22&btnG=Google+Search returns a number of pages. Most suggest the water is potable. None seems authoritative.

The S. NH guidebook says nothing about the safety of the water.

Ask the rangers next time you go there.

Doug

Aviarome
04-29-2006, 10:56 PM
Just wanted to add some additional info on chlorine. Chlorine is a wide spectrum disinfectant. At proper concentrations, chlorine can disrupt the cell membrane/wall, or diffuse across the membrane to cause damage via free radicals and reactive oxygen species. Like what everyone has said about evolution of resistance, some organisms have intrinsic resistance to chlorine (cysts and spores are notoriously resistant to chlorine, antibiotics, etc), and others develop resistance through sublethal exposure. In the case of chlorine, certain enzymes are produced that limit the production of free radicals, and thus, prevent damage/death. By the way, giardia cysts and cryptosporidia are pretty resistant to chlorine.

Antibiotic resistance is a huge concern in the medical field. More and more pathogens are gaining resistance to antibiotics. This in itself is a thesis, but I cannot emphasize enough about the proper use of antibiotics. More and more of the "heavy duty" antibiotics are becoming less effective.

aviarome

Lawn Sale
04-30-2006, 01:47 AM
Many, many thanks to all for clearing that up, it makes sense now. :)

Let's just hope we can stay ahead of the evolutionary changes.

I did manage to get out today, but not hiking as I'm still weary about my knee. But, I did 18 miles on the bike Thursday and am planning on another 20 tomorrow. I wish we could build a resistance to injuries, now wouldn't that be nice!

Lawn Sale
04-30-2006, 02:41 AM
I started another post on my visit to Hyrdo-Photon, the makers of the Steri-Pen in an effort to have some questions answered. The thread is here (http://www.vftt.org/forums/showthread.php?p=138950#post138950)

DougPaul
04-30-2006, 09:44 AM
Many, many thanks to all for clearing that up, it makes sense now. :)

Let's just hope we can stay ahead of the evolutionary changes.
They are relentless... You have to keep running just to stay in place.

Doug

Warren
05-01-2006, 06:51 PM
What I really was curious about is, after you've washed/rinsed something and it has dried (Water evaporated) do all the living organisms die once dry or can they still be harmful? Do you need to wash and rinse with safe water?

Please correct me, someone, if I am wrong.....

Even a disinfectant soap and air drying wont kill all organisms on whatever you are washing. See Lawn Sales comments near the start of the thread in regards to need a certain concentration of a "sterilizing agent". I think for the common man boiling is pretty much considered "the kills all the living organisms" treatment. Soap and water helps clean it and removes whatever degree of stuff, living and non living on said item.

For the record even after this thread, I'm still a treat or not based on personal judgment. If I'm with someone else who treats or is unsure, I treat. Some water is bad, some is not. I personally think poor group/individual hygiene is more of a problem in this regards.

When treating I'm pretty sold on aqua mira, I carry iodine as a backup, but try not to use it as I drink less water due to the taste. I prefer an inline filter to all other filters at this point, except in larger groups or during severe droughts where the reach of a hose and a pump can be handy.

jrichard
05-01-2006, 08:20 PM
When I do treat water while hiking, I usually use AquaMira or iodine.

However, while scanning though the most recent AMC outdoors, I noticed that undisolved Aquamira drops are extremely toxic.

I wonder exactly how toxic. And what the likelyhood is of getting poisoned from the treatment vs getting sick from the water itself.

rhihn
05-08-2006, 10:20 PM
Someone just sent me these sites. I'd be interested in any input on this. particularly from Lawn Sale. I'm not thinking of going out and buying one, but I'm just wondering how effective this LifeStraw really is, given size of giardia.


http://news.bbc.co.uk/2/hi/africa/4967452.stm
http://www.lifestraw.com/