Greetings all,

I am a little confused when it comes to water filtration and purification. Are there systems that do both ?

I am in the process of expanding my small bug out bag not that time, money, and space allows me to and I was looking into purchasing a water procurement system such as a Gravity Works 4.0L or Katadyne Basecamp Pro. Assuming I find a water source, would I need to do anything else to the water after it has been run through the filter ?

Also, do any water filter systems exist in which the filter is permanent and never needs replacing ? (just an occasional washing).

Lastly, if the two filter systems I am considering are no good please provide opinions as to what should be considered in their stead and any additional tips or advice regarding water procurement and handling would be greatly appreciated.

Can't wait for the brains to come in and pull this apart.

Filter gets chunks out of water to a point.

Purifier kills bacteria still in water that is too small for filter to get out.  Can use bleach, water purifier tabs, or boil it.  Would highly recommend searching your main concerns to decide on time limits for stuff.  I know there are uv lights and other stuff, I was just listing some stuff I have played with over the years vs. stuff I have not.

My biggy always comes when someone asks about gasoline or something else dissolved in water.

Not sure if activated charcoal would do that or not. 

No matter what the system, I keep something like coffee filters around not just for coffee grounds but as a pre-filter so the good filter setup sees a lot less much and what not.

Anything I do now is for hunting camp or car/jeep camping.

This is mostly a tag to see if my definitions are close to right and to learn.

I generally go search out the old reverse osmosis threads cause lots of stuff got discussed in them years past.  Expy37 had/has the reverse osmosis stuff that I recall the posts being about.

Filtering is simply the mechanical removal of debris and/or microbes from water. Purification involves killing/neutralizing pathogenic microbes, either by chemical means, UV light treatment, or boiling.

I am home sick from work, so being wordy or thinking aloud I guess.  I will let the other post stand as an example of that.

Anyway, where does the gas disolved in water come into play?

gasoline in water and/or MTBE

they make filters for MTBE iirc.
think of being caught in an area that has had massive flooding or being in an area downstream of this event; raw sewage and gasoline/diesel filling stations have flooded and spilled out of containment.  Perhaps it has contaminated the municipalities water system also.  Fuel floats on water and partial emulsions with water also.
Think of filling an empty fuel can with water, the water is still going to smell and taste like fuel.
You could boil it and try to flash the hydrocarbon off or try to distill it; might still want to run it through an activated carbon filter to absorb any nasties and make it taste better.

Once you start introducing heavy metals and  chemicals, filtration and purification get exponentially more complicated and or expensive.  

For most natural water souces, filtration is generally adequate.  Viruses tend to cause the most problems with filters due to thier size.  Fortunately, the majority of viruses occur in third world dumps, but any disaster that mixes sewage with water sources will create the same threat vectors.  The most economical means of dealing with viruses is via chemical means for purification.  There are several systems on the market that both filter and provide a chmical matix for purification.  Activated charcoal offers some protection against some chimicals, but both chemicals and charcoal have limited shelf lifes where their efficacy drops off.  

Iodine is one chemical that does well against viruses, but not all hardened bacterial spores.  If suspended in water, it will last several years.  I still have iodine crystals in Polar Pure bottles over 15 years old.

MSR used to make a battery operated MIOX device.  It basically, converts rock salt and water into a mixed oxidant solution with an electric charge similar to the solution mixtures like Aqua Mira.

Regardless of your filter/purification system, you should store potable water.  Setting up a distiller isn't difficult, but requires a lot of fuel and effort when dealing with chemically contaminated water.   Rain catches are another simple and effective method for moat areas.

The closer you are to urban areas, farm runoff or flood plains, you really need to consider a chemcial means of purification and activated charcoal integrated into your filtration.  If your primary water sources are compromised short term, you can likely get by with stored water, boiling, filtering/purification; however if it's a long term, large scale contamination event, your stored water will get you started and your eventual bug out will rely on those other mechanical or chemical means.

As to UV, it works, but the water souces really need to be clear and they don't help with heavy metals or chemicals.  Several of the silver impregnated ceramic filters have proven effective for bacterial and viral contamination and are good long term filters.  

I have recreational water filters and treatment, but I also have homestead filtration and treatment.  We have a well and spring fed lake, along with decent rain fall, so the homestead is pretty robust.  Still, having a means to deal with viruses and other contaminates offer solid options to bugging out or to home if required.

ROCK6