K.L. Davis
03-05-09, 19:47
A lot of folks would be surprised to find out that by far the majority of all water that is on the surface of the Earth is far from pure... the contaminates run from chemicals to biological risks and natural toxins.
What is in the water that you drink in a field/survival setting can be a great concern -- having had the dubious opportunity to contract at least a few of the better known GI disorders, water purity is something I take quite seriously.
Unlike the discussion in the Preparation Forum, this will talk about "point of use" water and the steps available to help ensure that the water you are drinking is as safe as you can make it.
There are a few methods of on site disinfection, some work better than others, some are more practical and some require special equipment or supplies -- we'll discuss the five most common techniques, their effectiveness and drawbacks, and hopefully give you enough information that you can decide which is best and effectively employ it.
First, let's talk about some of the more probable concerns to the water you find... Oddly enough, even though you may be miles from anything that seems like civilization, there is always the chance of chemical pollution -- but, as we are typically dealing with wilderness settings, we'll move this to the back of the list. Of course there is the obviously dirty water, that which is muddy, clouded or carrying algae growth; lot's of times what you can see in the water may not be all that bad for you by itself, but it is at best unpleasant and in many cases a sign that the water has been stagnant. In any case, the presence of these large enough to see additions to the water should be removed, as they make further disinfection more difficult.
The big problem that we have to deal with is biological... microbes, viruses, pathogens, bacteria, protozoa and all those other things that hide right there in plain sight. Some of the threats include Cryptosporidium, Giardia, Botulism, Cholera, Salmonella, Typhus and many others... even some wonderful things like parasitic flukes and worms. These tiny critters can find their way into the water in several ways; but the most common is the unpleasant fact that some random animal may have chosen a spot just a ways upstream as its final resting spot... or the equally disturbing idea that various other animals have been using your clear, cool stream as a jungle loo -- think of it as the call of the wild.
Before we get into the disinfection methods below... let's revisit that dirty water, we want to get it as clean as we can, but what we are talking about is not the same as the Filtration process we will talk about later, that is disinfect the water... right now all we want to do is get the big chunks out. Of course you could use your dedicated water filter, but you are drastically shortening the service life of the device.
So, most of the time we can filter water by pouring it through cloth or paper, the best method is to pour the water through layers of clean cloth or paper, until it is clear (or is not getting any clearer), then let the water set for at least 30 minutes to allow any remaining particulates to settle, then pour our siphon the clean water from the top. You can add a little Aluminum Sulfate (alum) to the water as a flocculant, this will make particulates "coagulate" and filter/settle better.
Boiling - Boiling is the old tried and true method of disinfecting water, it is simple and very effective, but does have its drawbacks and limits; first off, boiling requires something to boil the water in, and something to get it hot enough to boil. I'll not dig too deep into this really, but suffice to say that you can not boil water in a plastic bottle, nor will you get it hot enough just by rubbing your hands together; if however, you do have the means and equipment to boil water, it is an excellent way to disinfect water.
We all know that water boils at 212F (100C) at Sea Level, and that the boiling temperature drops as you get higher in altitude... the truth is that in order to effectively kill off everything in the water, you would need to heat the water above its boiling temperature, but this is something that you can not do without an autoclave or pressure cooker... odds are, you don't have either of those in your Personal Survival Kit.
There are lots of charts and scales on boiling disinfection times... But, to keep this simple, if you are using boiling to disinfect water in a Survival Situation, heating it to a full "rolling" boil and holding it for long enough to say "Wow, it's really boiling" is really all you need, keep in mind that the water is over 200F for some time on its way to boiling, and also for a while on the way back down -- and the longer you keep the water boiling, the more fuel you are using and the more water you losing.
So, my advise here is that boiling is still one of the best ways to disinfect water and should be considered in any situation in which you have the means to do so; nearly every professional, governmental and medical source I know of says that boiling water for one minute is all that is usually needed, many recommend boiling for three minutes if you are over 6500 feet, and the boiling point does not fall below a useful temperature until you are above 17,000 feet -- if you find yourself there, hopefully you planned ahead for that event.
Filtration
Chemical Disinfection - Chemical treatment is a very simple and reliable method of disinfection. The common chemicals used include: Iodine, Chlorine and Chlorine Dioxide, each has its advantages and disadvantages. Before we get too far into this, it is important to note that the effectiveness of chemical disinfection is notably reduced if if the water is dirty or murky. While they may not seem big to you and me, a single soil particle in the water can be a huge hiding place for viruses and bacteria, the chemical disinfectant may take many times longer than allowed to get into those particles and kill what hides therein -- So filtering turbid water prior to chemical treatment is a must... if the water is still murky or turbid, consider allowing more time for the chemical disinfectant to work, or even a second treatment.
As for the chemical choices... let's start with Iodine: Iodine has been used to treat water for decades. It can be found in several forms, liquid and tablets and packaged as a water purification product, or general first aid product -- Iodine, is not as effective as other methods for killing Cryptosporidium and Giardia and there are some ongoing concerns about possible health issues from its extended use... all that aside, using Iodine is far better than doing nothing and there are many that swear that it is all you need.
If you are using a commercial Iodine water treatment, follow the instructions for that product... if you are using Iodine disinfectant from a medical or first-aid pack, first read the label to make sure it is really Iodine and is the usual 2% solution. There are several brand names for Iodine solution, so check to make sure beforehand. The standard for using Iodine solution to disinfect water is 5 drops per quart/liter of water, and let set for 30 minutes -- if the water is murky or cold, you can double the amount of Iodine solution to 10 drops per quart/liter and ensure that the water is allowed to stand for the full 30 minutes.
Again, some folks swear by Iodine, but there are some concerns -- this is one thing that you really should talk with your doctor about before adding to your kit, some considerations include use by pregnant women, people with thyroid problems, and allergic reactions to Iodine. Those are the serious concerns, the lessor issues are that to many, Iodine just tastes horrible... it is actually suggested that you try a little Iodine treated water before you decide that it will be your preferred method of treatment; avid outdoorsmen also tend to have a preference for the taste of one brand of Iodine solution over others, I kid you not.
UV Light
SODIS(SOlar DISinfection)
What is in the water that you drink in a field/survival setting can be a great concern -- having had the dubious opportunity to contract at least a few of the better known GI disorders, water purity is something I take quite seriously.
Unlike the discussion in the Preparation Forum, this will talk about "point of use" water and the steps available to help ensure that the water you are drinking is as safe as you can make it.
There are a few methods of on site disinfection, some work better than others, some are more practical and some require special equipment or supplies -- we'll discuss the five most common techniques, their effectiveness and drawbacks, and hopefully give you enough information that you can decide which is best and effectively employ it.
First, let's talk about some of the more probable concerns to the water you find... Oddly enough, even though you may be miles from anything that seems like civilization, there is always the chance of chemical pollution -- but, as we are typically dealing with wilderness settings, we'll move this to the back of the list. Of course there is the obviously dirty water, that which is muddy, clouded or carrying algae growth; lot's of times what you can see in the water may not be all that bad for you by itself, but it is at best unpleasant and in many cases a sign that the water has been stagnant. In any case, the presence of these large enough to see additions to the water should be removed, as they make further disinfection more difficult.
The big problem that we have to deal with is biological... microbes, viruses, pathogens, bacteria, protozoa and all those other things that hide right there in plain sight. Some of the threats include Cryptosporidium, Giardia, Botulism, Cholera, Salmonella, Typhus and many others... even some wonderful things like parasitic flukes and worms. These tiny critters can find their way into the water in several ways; but the most common is the unpleasant fact that some random animal may have chosen a spot just a ways upstream as its final resting spot... or the equally disturbing idea that various other animals have been using your clear, cool stream as a jungle loo -- think of it as the call of the wild.
Before we get into the disinfection methods below... let's revisit that dirty water, we want to get it as clean as we can, but what we are talking about is not the same as the Filtration process we will talk about later, that is disinfect the water... right now all we want to do is get the big chunks out. Of course you could use your dedicated water filter, but you are drastically shortening the service life of the device.
So, most of the time we can filter water by pouring it through cloth or paper, the best method is to pour the water through layers of clean cloth or paper, until it is clear (or is not getting any clearer), then let the water set for at least 30 minutes to allow any remaining particulates to settle, then pour our siphon the clean water from the top. You can add a little Aluminum Sulfate (alum) to the water as a flocculant, this will make particulates "coagulate" and filter/settle better.
Boiling - Boiling is the old tried and true method of disinfecting water, it is simple and very effective, but does have its drawbacks and limits; first off, boiling requires something to boil the water in, and something to get it hot enough to boil. I'll not dig too deep into this really, but suffice to say that you can not boil water in a plastic bottle, nor will you get it hot enough just by rubbing your hands together; if however, you do have the means and equipment to boil water, it is an excellent way to disinfect water.
We all know that water boils at 212F (100C) at Sea Level, and that the boiling temperature drops as you get higher in altitude... the truth is that in order to effectively kill off everything in the water, you would need to heat the water above its boiling temperature, but this is something that you can not do without an autoclave or pressure cooker... odds are, you don't have either of those in your Personal Survival Kit.
There are lots of charts and scales on boiling disinfection times... But, to keep this simple, if you are using boiling to disinfect water in a Survival Situation, heating it to a full "rolling" boil and holding it for long enough to say "Wow, it's really boiling" is really all you need, keep in mind that the water is over 200F for some time on its way to boiling, and also for a while on the way back down -- and the longer you keep the water boiling, the more fuel you are using and the more water you losing.
So, my advise here is that boiling is still one of the best ways to disinfect water and should be considered in any situation in which you have the means to do so; nearly every professional, governmental and medical source I know of says that boiling water for one minute is all that is usually needed, many recommend boiling for three minutes if you are over 6500 feet, and the boiling point does not fall below a useful temperature until you are above 17,000 feet -- if you find yourself there, hopefully you planned ahead for that event.
Filtration
Chemical Disinfection - Chemical treatment is a very simple and reliable method of disinfection. The common chemicals used include: Iodine, Chlorine and Chlorine Dioxide, each has its advantages and disadvantages. Before we get too far into this, it is important to note that the effectiveness of chemical disinfection is notably reduced if if the water is dirty or murky. While they may not seem big to you and me, a single soil particle in the water can be a huge hiding place for viruses and bacteria, the chemical disinfectant may take many times longer than allowed to get into those particles and kill what hides therein -- So filtering turbid water prior to chemical treatment is a must... if the water is still murky or turbid, consider allowing more time for the chemical disinfectant to work, or even a second treatment.
As for the chemical choices... let's start with Iodine: Iodine has been used to treat water for decades. It can be found in several forms, liquid and tablets and packaged as a water purification product, or general first aid product -- Iodine, is not as effective as other methods for killing Cryptosporidium and Giardia and there are some ongoing concerns about possible health issues from its extended use... all that aside, using Iodine is far better than doing nothing and there are many that swear that it is all you need.
If you are using a commercial Iodine water treatment, follow the instructions for that product... if you are using Iodine disinfectant from a medical or first-aid pack, first read the label to make sure it is really Iodine and is the usual 2% solution. There are several brand names for Iodine solution, so check to make sure beforehand. The standard for using Iodine solution to disinfect water is 5 drops per quart/liter of water, and let set for 30 minutes -- if the water is murky or cold, you can double the amount of Iodine solution to 10 drops per quart/liter and ensure that the water is allowed to stand for the full 30 minutes.
Again, some folks swear by Iodine, but there are some concerns -- this is one thing that you really should talk with your doctor about before adding to your kit, some considerations include use by pregnant women, people with thyroid problems, and allergic reactions to Iodine. Those are the serious concerns, the lessor issues are that to many, Iodine just tastes horrible... it is actually suggested that you try a little Iodine treated water before you decide that it will be your preferred method of treatment; avid outdoorsmen also tend to have a preference for the taste of one brand of Iodine solution over others, I kid you not.
UV Light
SODIS(SOlar DISinfection)