There seems to be a lot of water storage threads of late along with the typical how long does bottled water last question.
I thought I'd create this post to help those with this sort of question think through the problem and in the end answer the questions themselves. First lets focus on water and what makes it undrinkable to begin with.
Obviously water is water. Chemically it doesn't change much. However, chemicals and organisms can find their way into the water contaminating it and making it unsafe to drink.
Micro Organisms: There are really three classifications of microorganisms.
Protozoa: Protozoa like Giardia and Cryptosporidium among others are relatively speaking large microorganisms. These larger parasites are resistant to chemical treatment like chlorine or Iodine but are easily filtered out due to their large size. Nearly all backpacking filters are capable of filtering these kinds of organisms from your water.
Bacteria: Bacteria like Botulism, E Coli, and Dysentery are smaller than protozoa. These can all be treated with UV light, Chemical decontamination and in most cases can be filtered out by your typical backpacking filter. Beware that some bacteria are fairly small and will require more specialized filters. Bacteria like Legionellosis for example require filters measured in .0x range rather than .x range. So if your pondering whether to get the Sawyer .1 or the Sawyer .02 this might help answer your question.
Virus: Virus are even smaller and are also much more difficult to filter out with your typical backpacking filter. Like Legionellosis you're really talking .0x at a minimum and that will not be 100% perfect. To be more effective you need a reverse osmosis filter, UV light, or chemical decontamination. You can also boil the water of course. Luckily, virus are very species specific and are not common in the industrialized world's surface waters due to our widespread use of sanitation systems. But if raw sewage gets dumped into our water then all bets are off. And for those of you living in the third world you probably already know virus are a big threat.
Chemical: Chemical contamination can be broken down into organic chemicals, inorganic chemicals, and heavy metals/minerals.
Organic chemicals are those that contain oxygen/carbon molecules such as most of our pesticides, herbicides, oils, gasoline, etc. Exposure to these can be minimized by filtering water through activated carbon. Continued exposure to these chemicals lead to an increased risk of cancer and other ailments.
Inorganic, minerals, and heavy metals are a bit harder to deal with. Some will be dealt with by activated carbon or another media called zeolite. There are special filters to deal with arsenic for example. But your best bet when it comes to these things are nanofilters or reverse osmosis filters. Since nanofilters are typically hard to find reverse osmosis is your best bet.
So now that you know what contaminants you must deal with lets talk about these in the context of storage.
If the water you put into storage does not contain any chemicals or heavy metals then they will not be present in your storage water after any amount of storage time unless some how they are added after the fact. A sealed container is your first line of defense. However, be aware that chemicals in the plastics of your storage containers themselves can leach into your stored water. It is critical that you NOT use any plastic container that has ever held any sort of toxic chemical. In some cases certain plastics contain BPA which itself can leach into your water over time. Do your own research on BPA to determine if you think its a real risk or overblown hype.
Microorganisms are a different issue. Microorganisms have the ability to reproduce. And as such a very small number can multiply and transition from too few to be harmful into deadly with nothing more than time. This is important because most water filters do not eliminate microorganisms they simply reduce their numbers to a safe level. This is also true of many water treatment systems.
The key to managing microorganisms is to minimize their numbers and to keep them minimized. The municipal water system uses a number of techniques to do this but in the end they treat water leaving their facility with chlorine (or similar) to help keep the microorganisms from reproducing to a level where they become a threat while the water sits in your pipes or water towers. And to minimize contamination by organisms that might otherwise grow in these storage systems.
Chlorine, however, does not last forever. It will begin to break down and as it does any microorganism that managed to survive or that is subsequently introduced will begin to multiply. To minimize this threat it is recommended that you treat your water with additional quantities of chlorine on a semi regular basis. 6 months to a year.
Of course an alternative approach and one most water bottling plants use is to eliminate them from the equation all together. I'll leave it to you to determine whether they are kidding themselves or not but lets discuss their basic process. Keep in mind that not all bottlers are equal.
First they run the water through a reverse osmosis filter. Now reverse osmosis filters pretty much removes everything from the water including heavy metals and minerals. Some then re-add some of the trace minerals that can be beneficial to human health removed by the reverse osmosis filter.
Just to be sure many also run the water through a UV light to sterilize any trace microorganisms that remain eliminating their ability to reproduce. This heavily treated water is then placed into bottles that themselves where sterilized and then sealed air tight.
If you neglect the possibility of BPA leaching from the bottles and we assume that the plant responsible for this was properly run then this water will literally last forever without the need for any additional treatment. After all if there are no contaminants in the water to begin with and the possibility of new one being introduced is zero then the water will remain pure for as long as the bottle remains intact.
The key here though is that the bottle itself must be sterilized as well as the water. We wouldn't want our pure water to be contaminated by the insides of our storage container.
Now in theory if you treat your water with chlorine before adding it to a storage container and you ensure that every inside surface of that storage container has sufficient contact time with that chlorinated water and that storage container is sealed with an air tight seal. Well you should be able to obtain the same results. Of course ensuring sufficiently long contact time to all internal surfaces with sufficient chlorine levels is much harder than it sounds. But it is possible.
Now all of this might seem overkill. And to a certain degree it can be. There is nothing stopping you from simply filtering/treating the water from your storage immediately before consumption thus negating any sort of growth that might occur while in storage.
Anyway, I want to keep this somewhat brief (fail) so I'll end with that. I am sure this will open up all sorts of conversations. There are many people on this site with fairly good insight into these issues. But buyer should always beware.
I thought I'd create this post to help those with this sort of question think through the problem and in the end answer the questions themselves. First lets focus on water and what makes it undrinkable to begin with.
Obviously water is water. Chemically it doesn't change much. However, chemicals and organisms can find their way into the water contaminating it and making it unsafe to drink.
Micro Organisms: There are really three classifications of microorganisms.
Protozoa: Protozoa like Giardia and Cryptosporidium among others are relatively speaking large microorganisms. These larger parasites are resistant to chemical treatment like chlorine or Iodine but are easily filtered out due to their large size. Nearly all backpacking filters are capable of filtering these kinds of organisms from your water.
Bacteria: Bacteria like Botulism, E Coli, and Dysentery are smaller than protozoa. These can all be treated with UV light, Chemical decontamination and in most cases can be filtered out by your typical backpacking filter. Beware that some bacteria are fairly small and will require more specialized filters. Bacteria like Legionellosis for example require filters measured in .0x range rather than .x range. So if your pondering whether to get the Sawyer .1 or the Sawyer .02 this might help answer your question.
Virus: Virus are even smaller and are also much more difficult to filter out with your typical backpacking filter. Like Legionellosis you're really talking .0x at a minimum and that will not be 100% perfect. To be more effective you need a reverse osmosis filter, UV light, or chemical decontamination. You can also boil the water of course. Luckily, virus are very species specific and are not common in the industrialized world's surface waters due to our widespread use of sanitation systems. But if raw sewage gets dumped into our water then all bets are off. And for those of you living in the third world you probably already know virus are a big threat.
Chemical: Chemical contamination can be broken down into organic chemicals, inorganic chemicals, and heavy metals/minerals.
Organic chemicals are those that contain oxygen/carbon molecules such as most of our pesticides, herbicides, oils, gasoline, etc. Exposure to these can be minimized by filtering water through activated carbon. Continued exposure to these chemicals lead to an increased risk of cancer and other ailments.
Inorganic, minerals, and heavy metals are a bit harder to deal with. Some will be dealt with by activated carbon or another media called zeolite. There are special filters to deal with arsenic for example. But your best bet when it comes to these things are nanofilters or reverse osmosis filters. Since nanofilters are typically hard to find reverse osmosis is your best bet.
So now that you know what contaminants you must deal with lets talk about these in the context of storage.
If the water you put into storage does not contain any chemicals or heavy metals then they will not be present in your storage water after any amount of storage time unless some how they are added after the fact. A sealed container is your first line of defense. However, be aware that chemicals in the plastics of your storage containers themselves can leach into your stored water. It is critical that you NOT use any plastic container that has ever held any sort of toxic chemical. In some cases certain plastics contain BPA which itself can leach into your water over time. Do your own research on BPA to determine if you think its a real risk or overblown hype.
Microorganisms are a different issue. Microorganisms have the ability to reproduce. And as such a very small number can multiply and transition from too few to be harmful into deadly with nothing more than time. This is important because most water filters do not eliminate microorganisms they simply reduce their numbers to a safe level. This is also true of many water treatment systems.
The key to managing microorganisms is to minimize their numbers and to keep them minimized. The municipal water system uses a number of techniques to do this but in the end they treat water leaving their facility with chlorine (or similar) to help keep the microorganisms from reproducing to a level where they become a threat while the water sits in your pipes or water towers. And to minimize contamination by organisms that might otherwise grow in these storage systems.
Chlorine, however, does not last forever. It will begin to break down and as it does any microorganism that managed to survive or that is subsequently introduced will begin to multiply. To minimize this threat it is recommended that you treat your water with additional quantities of chlorine on a semi regular basis. 6 months to a year.
Of course an alternative approach and one most water bottling plants use is to eliminate them from the equation all together. I'll leave it to you to determine whether they are kidding themselves or not but lets discuss their basic process. Keep in mind that not all bottlers are equal.
First they run the water through a reverse osmosis filter. Now reverse osmosis filters pretty much removes everything from the water including heavy metals and minerals. Some then re-add some of the trace minerals that can be beneficial to human health removed by the reverse osmosis filter.
Just to be sure many also run the water through a UV light to sterilize any trace microorganisms that remain eliminating their ability to reproduce. This heavily treated water is then placed into bottles that themselves where sterilized and then sealed air tight.
If you neglect the possibility of BPA leaching from the bottles and we assume that the plant responsible for this was properly run then this water will literally last forever without the need for any additional treatment. After all if there are no contaminants in the water to begin with and the possibility of new one being introduced is zero then the water will remain pure for as long as the bottle remains intact.
The key here though is that the bottle itself must be sterilized as well as the water. We wouldn't want our pure water to be contaminated by the insides of our storage container.
Now in theory if you treat your water with chlorine before adding it to a storage container and you ensure that every inside surface of that storage container has sufficient contact time with that chlorinated water and that storage container is sealed with an air tight seal. Well you should be able to obtain the same results. Of course ensuring sufficiently long contact time to all internal surfaces with sufficient chlorine levels is much harder than it sounds. But it is possible.
Now all of this might seem overkill. And to a certain degree it can be. There is nothing stopping you from simply filtering/treating the water from your storage immediately before consumption thus negating any sort of growth that might occur while in storage.
Anyway, I want to keep this somewhat brief (fail) so I'll end with that. I am sure this will open up all sorts of conversations. There are many people on this site with fairly good insight into these issues. But buyer should always beware.
