Build a BOB: Water

Posted on: August 18, 2015

Water is another of those things that you truly can’t do without for any great length of time. Various and sundry experts have said over the years that the human body can survive roughly three days without hydration. Naturally, there are all sorts of variables that come into play with that, such as exertion level, overall health, and climate conditions. The average couch potato suddenly finding himself sweating his cojones off in the Mojave Desert will dehydrate faster than, say, a frequent marathon runner leisurely strolling through a Northwoods forest in autumn.

On top of that, keep in mind that the latter part of that “three day” time frame isn’t going to be pleasant. I mean, it isn’t like you’re just walking around lackadaisically and then an alarm bell suddenly goes off at the 72 hour mark and you fall over. No, severe dehydration brings on fun stuff like dizziness, lethargy, confusion, fever, even coma. Any of those sound beneficial for surviving a bug out? Yeah, I didn’t think so. Kind of hard to find your way to your bug out location when you’re comatose.

Water, though, can be problematic. Water is what it is. By that, I mean you can’t shrink it down, you can’t compress it, and you obviously can’t dehydrate it. One gallon of water weighs a bit more than 8 pounds. You can’t get around that fact. One gallon of water takes up 231 cubic inches. That’s another fact that won’t change.

In other words, if you’re traveling on foot, you’re not going to be carrying a whole lot of water with you.

What I suggest is a two-pronged approach to this problem. First, carry some water with you. Second, carry in your BOB the means to filter and disinfect additional water you source along the way.

Water containers

There are roughly a bazillion different water bottles on the market today. As with most things in life, you get what you pay for. I recommend going with stainless steel if you can afford it. A steel bottle can be used to boil “wild” water to ensure all parasites are killed. Aluminum bottles might work for that purpose but various studies have found that aluminum can leach into the water over time. Short term, probably not that big of a deal in the grand scheme of things. But, if you can avoid the issue altogether by investing in a stainless steel bottle, do so.

If you go the metal bottle route, be sure to select one that allows you to remove all plastic pieces, such as tethers that keep the lid attached to the bottle. Otherwise, this plastic will melt if you need to boil water in the bottle.

Go with a 1 liter size bottle, if you can. Many water purification products, such as tablets, use 1 liter as the standard amount of water per dose. Having a container that size just makes things easier all around.

I recommend having at least two such water bottles in your BOB. Both will hopefully be full when you begin your journey. Most people can probably carry 2 liters of water without undue strain. However, and this is important to remember, 2 liters is only equivalent to about ½ gallon of water. If you’re traveling on foot, you could go through that much water in half a day or so, depending on the climate and such.

The reason for multiple bottles is it gives you the option of using one bottle to disinfect water while still having the other one for drinking as you move. Water purification tablets, for example, aren’t instant. They take time to work.

Another option is to invest in a hydration bladder for your BOB. This is basically a large, heavy duty bag that fits into a pouch in your pack. You fill the bag with water and drink it from a flexible straw that loops through the pack and over your shoulder. I have mixed feelings about these products. On the one hand, they allow the user to carry a fairly substantial amount of water somewhat easily. But, these bladders could prove difficult to clean in the field, especially if they become tainted with something. I’m not saying to buy them and I’m not saying to avoid them. Just keep in mind they can be difficult to maintain when conditions are less than ideal.

One product in particular I highly recommend is the Aqua Pouch Plus with Water Purification Kit sold by Survival Resources. It serves as an excellent backup to your primary water bottles and such. The pouch is made from a very heavy duty plastic and is gusseted at the bottom, allowing the bag to stand when it is full. It has grommet holes at top, so you can loop cordage through and carry it easily. The pre-filter device allows you to use coffee filters to remove dirt and such before actually disinfecting the water.

Speaking of water disinfection….

Water filtration and disinfection

Lakes, rivers, streams, these are all what I refer to as “wild” sources of water. As you plan your bug out routes, try to incorporate visits to these bodies of water so you have the opportunity to resupply as needed.

Never, and I mean NEVER, drink water directly from one of these wild sources without treating it first. While it might look crystal clear, odds are good that the water is teeming with microscopic nasties that will do a number on your body. There are two ways of dealing with those bugs and such – filtration or disinfection.


As might be obvious, this involves removing the bad stuff from the water through the use of one or more filters. The filters might be ceramic, glass fibers, or some other material. These devices generally work rather well, provided you’re using a product from a reputable manufacturer. In general, water treatment isn’t an area where I’d want to rely upon some no-name, fly-by-night company.

When it comes to purchasing water filtration gear for the BOB, you’ll want something compact yet robust. Sawyer makes an awesome mini-filter that will fit in the palm of your hand. Lifestraw is a bit larger but also works very well. Some companies, such as Aquamira, make water bottles that have the filters built right in. All you do is fill the bottle with the questionable water and drink through the filter. However, those bottles are plastic, not stainless steel, so you won’t be able to use them to boil water. Just something to keep in mind.

No matter which kind of filtration device you use, it will work better and more efficiently if you pre-filter the water. Yeah, I know, that sounds a lot like washing dishes before putting them into the dishwasher. The idea behind pre-filtering is to remove the visible debris in the water before running it through your Sawyer Mini or whatever. Simply pour the water through a coffee filter, bandanna, or some other similar material to remove the dead bugs, dirt, and other debris.


Rather than removing the parasites and other nasty critters, disinfection works by killing them off. The simplest way to do this is to boil the water. You don’t need to boil it for a certain length of time, either. As long as the water is brought to a rolling boil, you’re good. If you feel better by boiling it for 5, 7, 10 minutes or whatever, go ahead. This method of disinfection is why I’ve hammered home the point about carrying a stainless steel bottle in your BOB. It is easy, with no moving parts to wear out or components that could fail at a crucial time.

Next on the disinfection list is water purification tablets. There are two basic types – iodine based and chlorine dioxide based. When given a choice, most people prefer the latter as the resulting water tastes better. Something to remember, though, is that these tablets have a finite shelf life. You want to be sure the tablets you’re carrying are still viable so you’ll need to be sure to check them periodically.

Polar Pure is another great option. Basically, you add water to the little bottle to make a solution that you then add to the water you are going to drink. This particular product is highly recommended by my good friend and fellow author Scott B. Williams.

The takeaways from all of the above are:

1) Have multiple water containers in your BOB. Keep them filled until you bug out, rotating the water periodically.

2) As with any other survival goal, have at least three ways to render found water potable. I suggest at least one way to disinfect and one way to filter, then choose one more method or device from one of those categories to meet the minimum three.

3) Test out your chosen methods or devices well in advance of truly needing them. Have a full understanding of how they work and how to clean them.

Get caught up on all installments in this series here:
First aid / Hygiene
Signaling and Communication
Choosing the Pack or Container
Common Mistakes
Useful Odds and Ends

2 thoughts on “Build a BOB: Water

  1. Slight mis info given when it comes to boiling water. Because its based on contact time to the heat source, you have to boil longer at higher altitudes so when in ohio bring to a rolling boil is suffincent contact time to the heat source to kill off everything not the case in denver because water boils more easily at higher altitudes water is brought to a rolling boil more easily giving you less contact time to the heat source and more than likely not killing everything in the water

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