(NaturalNews) Water is the single most crucial commodity necessary for human survival. A person can live for weeks without food, but without water it's a matter of a few days.It's difficult to stockpile enough water to last for any extended length of time, and it's even more difficult to carry enough water to last more than a few days if you're on the move, especially on foot.Accordingly, any realistic plans and preparations for a SHTF scenario must include methods for purifying water. There are many tools and techniques for doing so, but with some basic knowledge you can also find or produce drinkable water even if you don't have purification equipment handy.A recent article posted on thewebsite titled "Water Purification for Preppers" details six basic methods of water purification. If you don't already know something about the different techniques for obtaining potable water, the piece is an absolute must-read.Although the article goes into deeper (and very useful) detail, here is a list and basic description of all six techniques:-- If you have a heat source, boiling water is one of the simplest ways to purify it enough to make it drinkable.If possible, strain the water through a filter or cloth before boiling it. A coffee filter works fine for this. Bring the water to a boil over a heat source for at least five minutes, but it's best to let it boil for up to 20 minutes to make sure all the organisms it contains have been killed. This will kill any bacteria in the water and will vaporize most chemical contaminants. Boiling will not, however, get rid of metals, minerals or solid materials.-- Using drops or tablets is another very easy way to obtain safe drinking water. Every bug-out bag should contain either water purification drops or tablets, partly because they are lightweight and easy to carry, but also because they are so easy to use. If you are on the move and don't have time to stop and purify water that you find along the way, you can fill a canteen or jug, add one drop or tablet per quart of water and keep moving.It takes about half an hour to kill all the bacteria, and the water will not taste all that great, but in a survival situation, that won't be a big concern -- besides, you can add a little salt or flavoring to it to improve the flavor.-- There are several types of water-purifying devices. Some are handheld and quite portable; others take up space and are better suited for home use. Hand-held pump purifiers and water bottles with built-in purifying filters are best if you're traveling on foot.Every bug-out bag should contain a LifeStraw Personal Water Filter. They are small, lightweight and inexpensive, but could prove to be a lifesaving addition to your list of bug-out bag essentials.- Liquid bleach such as Clorox (unscented, non-soapy) is effective for killing bacteria in water.The rule of thumb is six drops per gallon or two drops per liter or quart. Keep in mind that bleach is sensitive to high heat or freezing temperatures. Store it at room temperature and it should last up to a year.-- Commonly known as "Pool Shock," calcium hypochlorite is a good alternative to bleach because it has a longer shelf life. For more details on how to use it along with the correct ratios, visit the link included below.-- You can collect water, even when there isn't a source nearby, by building a simple solar still. All you need is a hole in the ground, a container to collect the water in, a plastic sheet and a few rocks. For an explanation and a diagram, click on the link below.