There’s no shortage of water filters and purifiers on the market today, and it’s pretty easy to find one that is the perfect match for almost any situation imaginable.  However, it’s also easy to focus more on design as opposed to function, and this can leave us vulnerable to exposure from waterborne pathogens if we’re not careful.  Let’s take a closer look at the difference between filtration and purification, and how it can impact our preparedness efforts.


Filtration does exactly that- it filters out particles in the water.  Some of these particles can be large and visible whereas others can be microscopic.  The effectiveness of a filter will depend on the size of the microscopic holes that trap particles.  Most good filters for wilderness or survival applications will block a variety of harmful bacteria, protozoa and viruses that include Salmonella, E. coli, Norovirus, Hepatitis A, Giardia and Cryptosporidium.  Most filters also trap harmful minerals and heavy metals as well.  However, filters don’t remove contaminants that are smaller than the diameter of the pores in the material.  Consequently, depending on where you source your water, filtration may not be enough.


In some cases, particles in water should be filtered in stages in order to prevent filters from clogging.  This can be as easy as creating an improvised charcoal and sand filter or using a piece of cloth to trap particles.  One the larger particles have been removed, the water can then be passed through the main filter.  Just remember that pre-filtering is just an intermediate step, and it will most-likely contain microorganisms that can make us sick.


Purification is intended to kill the microorganisms that filters trap, in addition to others that remain in the water afterward.  However, purification doesn’t filter water, and particles may remain after the process is complete.  Purification is considered to be the most-thorough way to make water safe to drink, and all you need are some tablets which are both space-saving and inexpensive.  The downside is that purification can take time, sometimes 30 minutes or more, and tablets also alter the taste of water somewhat.

You can also purify water through boiling, but this requires you to set up camp and build a fire beforehand.  Consequently, it may not be a practical option depending on the situation at hand.  However, boiling is also the best way to make water potable as it doesn’t affect the taste, and there are no chemicals involved in the process.

Finally, there is UV purification, which involves shining ultraviolet light into water for a specified amount of time.  The energy waves from the light will kill most harmful pathogens without altering the taste of the water as well.  However, you need a good light in addition to having the right container so the light can reach all of the microorganisms in the water.   This may or may not be a practical option in the field depending on the situation at hand.

At the end of the day, it’s probably wise to include both filtration and purification into your preparedness efforts in order to give yourself access to the safest water possible.  Just make sure that you choose products that are rated to remove as many pathogens as possible so that you can minimize risk associated with water-borne contamination in the field.