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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
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 don’t want to write a dissertation and you don’t want to read one, I’ll 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 let’s go into source supply first, since that’s where it all begins.
I have been hiking for many years, and always hear people say, “this is safe”, or “that is unsafe” when they don’t 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? It’s impossible to tell when you’re 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 can’t, 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, it’s just that, a myth. Running water mixes contaminants so you’re 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 don’t 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 you’ve 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 don’t 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 don’t 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 didn’t 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, here’s how to obtain safe water.
There are three areas of target organisms to worry about. I won’t 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 won’t 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 µm (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 µm.
3. Protozoa: Protozoa range in size from 1 to 20 µm. Crypto (Cryptosporidium Muris and Parvum) and Giardia (Giardia Lamblia) are in this group.
Right off the bat you’ll 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 they’re 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 won’t remove viruses, which is why you need to disinfect using a method I’ll 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. Don’t 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 that’s 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 “catch-all” 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 “purifiers” 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 isn’t 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 wouldn’t 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 you’d 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 it’s called disinfection, which is the killing of pathogenic (disease causing) organisms.
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 don’t want to write a dissertation and you don’t want to read one, I’ll 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 let’s go into source supply first, since that’s where it all begins.
I have been hiking for many years, and always hear people say, “this is safe”, or “that is unsafe” when they don’t 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? It’s impossible to tell when you’re 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 can’t, 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, it’s just that, a myth. Running water mixes contaminants so you’re 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 don’t 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 you’ve 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 don’t 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 don’t 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 didn’t 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, here’s how to obtain safe water.
There are three areas of target organisms to worry about. I won’t 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 won’t 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 µm (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 µm.
3. Protozoa: Protozoa range in size from 1 to 20 µm. Crypto (Cryptosporidium Muris and Parvum) and Giardia (Giardia Lamblia) are in this group.
Right off the bat you’ll 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 they’re 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 won’t remove viruses, which is why you need to disinfect using a method I’ll 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. Don’t 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 that’s 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 “catch-all” 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 “purifiers” 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 isn’t 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 wouldn’t 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 you’d 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 it’s called disinfection, which is the killing of pathogenic (disease causing) organisms.
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