I recently answered a question in response to an e-mail about what else could be done in a primitive environment to clean water beyond the simple gradient filter of dirt-sand-gravel using one or more buckets.  

The answer depends on the assumption of how primitive a situation should be assumed.  

If no buckets are available then one could use animal skins, canvas or plastic tarp to take the place of the bucket. 

If fire were available, the filtering action would be improved if some charcoal (made in a primitive fire) were added above the rocks and below the sand or dirt.  

Sponge (if available) over the output holes, fine cloth and many other gradient filter items can be added to help the filtering process if available.  The slower the water moves through the filter the better (clearer of particles) the results.

Another way would be to dig a shallow well by hand near a stream or body of water and wait for the water to seep through the dirt into the hole.  

All particle filtering approaches (excluding the distillation processes) assume there is not something (a chemical) in the water that is fully dissolved in great quantity that is toxic.  Charcoal will remove hydrocarbons and some lead, but in general doesn't work for most non-organic toxins as far as I currently know.  Dirt and sand removes large particles only.

If no fire is available, and a plastic tarp is available then a distillation tent can be made.  This is a tent made over a body of impure water. Heat from below evaporates the impure water and it condenses on the inside of the tent (cooled from outside) and runs down the walls where it is captured.  These are more effective when there is a definite heat difference between two sources that are close to each other. For example if you have a hot spring or hot earth and can use cool air or a cold river to condense the water vapor.  Distillation tents were originally designed to work with the suns heat, but will work with any other natural heat source.  When the temperature gradient is small they will still work just slower.  In general one would measure the temperature of the ground and the air above and decide if this is a good method.

Another way to filter water is to use naturally growing algae and set up some slow flow settling tanks (made out of plastic tarps over holes in the ground for example) possibly under a distillation tent (two processes going at once). The idea is water enters one end of each tank and filters through a tortuous path (passably lots of rocks) with lots of growing alga. Comes out the other end to enter another tank of same construction. The longer the water takes to get from end to end the greater the filtering. The idea is the alga eats up what's dissolved and the larger particles settle to the bottom.  

Capturing water vapor out of the after PS fog may be possible with a little experimentation.  String up sheets or cloth with lower end in a bucket.  As the water condenses out of the air it runs down the fibers into the bucket.  At this point I am not sure what material would work the best.  It would probably be something that has affinity for water with holes in it so some air movement is possible.  

The Zetas have indicated that water from the air would be more pure than water from the ground.  Capturing rainwater any way you can is an obvious one.    

Purifying the water: If electricity (even a small amount) is available one can make colloidal silver and use this to kill the bacteria in the water instead of boiling it.  One needs a small amount of pure silver (99.9%) and a way of making a small amount of distilled water (small distill tent) to do this process. 

If no electricity and no fire then pick a tree or plant (possibly garlic like) with the most antibacterial properties and chop it up and put it in the filter near the output. In such as way that the water is in contact with these chips for as long as passable.  Oak wood barrels have been know to keep water reasonably pure. Find the tree or plant that rests the most bugs and fungus and you have a potential winner. I think the cedar tree is a good candidate. 
    
I hope this helps by collecting a few concepts in one write-up.



The Temple of Sacred Healing Arts wrote:
> Dear Mike,
> WindEagle asked me to email you regarding water filtration systems.  We 
> have and are getting more in the way of water purifiers from the Zeta 
> website, but we are also concerned about long-term filtration (i.e. 
> after the filters are all used up).  We found the following information 
> - what do you think?  We are thinking at that point our best option 
> would be to filter with this method and then boil the water.  We 
> couldn't find anything on the Zeta site that would be more 
> "savage/primitive" - are we not looking in the right place?
> Thank you,
> Katie
> 
> 
> 
>  
> 
>  
> 
> This article gives a quick and easy method of producing your own 
> expedient earthen water filtration system from common materials found 
> around the home.
> 
> Earthen filters are effective for filtration when radioactive fallout is 
> suspected. They are more effective and reliable than distillation, 
> ion-exchange filters, or charcoal filters.
> 
> NOTE: This example describes how to construct a water filtration system. 
> Filtering is not the same as purifying. Water filters "screen" or 
> "strain" tiny particles out of the water that passes through the system, 
> such as unwanted sediments and trash. On the other hand, however, a 
> water purifier destroys any microscopic organisms that may be present in 
> the water and that are too small to be captured by a filtration system.
> 
> So, keep in mind that even after water has been filtered, it still must 
> be disinfected or purified before consumption (This is very important).
> 
> 
>       Instructions:
> 
>     # Create a water filtration container by perforating the bottom of a
>       clean 5 gallon can, bucket or waste basket with holes punched
>       within 2 inches of its center.
>     # Place a one and one-half inch layer of washed pebbles in the
>       bottom of the container.
>     # Cover the pebbles with one thickness of terry cloth towel or other
>       porous cloth.
>     # Scrape the top four to five inches of soil off the ground to get
>       below fallout contamination (assuming nuclear fallout is present
>       or suspected), and then dig enough dirt to fill the container with
>       8 inches of this soil, packing it tightly against the sides.
>     # Cover the layer of soil in the container with another thickness of
>       towel and that with another inch or two of pebbles.
>     # Suspend the container over another clean vessel and then pour
>       contaminated water into the top container. 
> 
> "Clean", clear water will come out the bottom at the rate of about 6 
> quarts per hour.
> 
> NOTE: The term "Clean" does not imply that this filtered water is safe 
> for drinking. Always be sure to purify all filtered water before using 
> it for drinking, cooking or bathing.
> 
>