Water Filtration
Make no mistake contaminated water can make you sick and can kill you. There are three major organic contaminates of water; Protozoa, Bacteria, and Viruses. They are all microscopic. Protozoa and their cysts (eggs) are the largest in size at 1-15 microns, followed by bacteria at .2 – 2 microns in size. Viruses are the smallest and can be as small as .005 microns in size.

All of the water you collect from an outside source will need to be filtered or purified. Rain water should start out cleaner than water from a pond, but I treat all water collected outside the same. I treat any outside water like it is contaminated and needs purification.

There are many products available to purify water. Some products are geared for small amounts of water while on the go and others are geared for a large quantity of water at a set location. There are a few products that try to accomplish both. We are most concerned about purifying large quantities of water so that is what I’ll cover most.

Filtration – Water is passed through a filter. The filter has small openings. When water is put through the filter, anything in the water that is larger than the filter opening is prevented from passing through and is removed from the water. Water filters openings are measured in microns. Since bacteria size is between .2 and 2 microns in width, a .2 micron filter would filter out bacteria and would also filter out protozoa which are larger than bacteria. Viruses are the smallest living organisms known to man can measure as small as .005 microns.

It is not cost effective to make a .005 micron filter to remove free floating viruses. Many filter manufacturers claim that their .2 micron filters are water purifiers based on the fact that viruses usually attach themselves to larger microbes. As the larger microbes are filtered out, so are the attached viruses with them. There is probably a good basis for that argument. The unfiltered/free floating viruses would be a small percentage when compared to the number of attached viruses that get filtered. Additionally, because of the high water standards in the US it is very unlikely that any US water is a source of Hepatitis, Norwalk, AIDS or any other virus. But to be absolutely sure of safety, filtered water should also be chemically treated. Some manufacturers include a chemical treatment component in their filters.

Filtration Systems – There are two major types of filtration systems. The first is Gravity Drip and the second is Pressure Flow. Both types have pros and cons. Whichever one you choose, they both accomplish their intended purpose of filtering water. There are several questions you need to answer as you decide what type of system to buy. Will it be used strictly at home or do you need it to be portable? How much drinking water do you need it to produce? How quickly do you need it to treat the water?

Pre-Filtering – You should pre-filter all murky water as follows: Let the murky water settle over night. Pour the clear water from the top of the settled water through a piece of tightly woven fabric, a paper towel or a coffee filter. Be careful when pouring off the clear top water that you do not agitate and re-suspend the settled debris.

Gravity Drip Filters – These systems can produce large quantities of water but you can’t rush them. Gravity drip systems have two chambers. The upper chamber houses the filters and unfiltered water. The lower chamber holds the filtered water.

Water is filtered by pouring it into the upper chamber and letting it flow through the filters into the bottom tank. The flow rate depends on the number of filters you have installed, how much water is in the upper chamber, how dirty the source water is and how clean the filter is. The number of filters you install will depend on how much water you need filtered each day. A single filter is plenty for 2 people. If you are filtering water for a big family you will want to install multiple filters. Most single filters can produce at least 1 liter of water per hour.

The fuller the upper chamber is, the greater the flow rate because of the increased pressure pushing water through the filter. As water is filtered, debris will begin to clog the filter openings. When you notice a reduction in the flow rate, scrub the filter with a “Scotch Pad” to remove debris and restore the flow rate.

Ceramic Gravity Drip Filters – All ceramic filters are made by Doulton or Aqua Cera. They generally have a ceramic outside with a charcoal core and impregnated silver. The outside ceramic filter can be cleaned with a “Scotch Pad” when it gets dirty and will filter thousands of gallons of water. The center charcoal core has about a six month life once it is first used. The charcoal core is used to help remove odors and bad taste from the water. The ceramic filter is the part that gets rid of all the bad little bugs. Once the charcoal is used up you can still use the filter, but the water may not taste as good as before.

Berkey Water Filters – Berkey makes 8 different systems to meet almost any need. The holding tanks have a 1.5 gallon to 6 gallon capacity and are made from stainless steel or high impact plastic. Berkey has two types of filters. One is the “Black Berkey”. It is made from a combination of 6 types of media. The filtration is said to be so good that Berkey considers the “Black Berkey” filter a water purifier. The other filter is a standard .2 micron ceramic filter made by Doulton. Both filters are rated to filter 3,000 gallons before the charcoal is used up and they need to be replaced.

Black Berkey filters are currently 2 for $107.  Here is a link.

Katadyn Water Filters – Katadyn has a wide variety of water filtering and purifying products. They range from gravity drip home systems to small take along filters and chemical treatments for hiking and wilderness survival. My favorite two Katadyn products are the Ceradyn Gravity Drip Filter System and the Katadyn Combi Filter system. The Combi is my favorite small system for Bugging Out. These are among my favorites because each filter can filter up to 13000 gallons of water.

The Ceradyn Filter is a .2 micron, cleanable, Ceramic/Carbon impregnated filters. Each filter can filter 13,000 gallons of water.

Ceradyn filters are currently $69 each. Here is a link.

Katadyn Combi – Another filter on my favorites list is the Combi.  The Combi is only 12” high by 2.4” in diameter.  It has a .2 micron, cleanable, ceramic/silver impregnated filter with a refillable activated carbon cartridge.  The filter has a 13,000 gallon capacity.

The Combi comes with a pre-filter and bottle adaptor so that filtered water goes directly into an attached water bottle or attached 2-liter soda type bottle.  The Combi is operated by placing a hose with the pre-filter into the source water and pumping the piston top to filter the water.  An adapter is available to attach the Combi to your home or RV faucet.  The cost is currently $159

Aqua Cera Filters – Aqua Cera make two main filters. The Black CeraCarb which is much like the Black Berkey and CeraSyl Plus. Both are .3 Micron filters and come in either 7” or 10” lengths. Aqua Cera also makes stainless steel and plastic filter housings like Berkey and Katadyn. The volume the filters can handle is comparable to the other companies, 3,000 gallons for the CeraCarb and 13,000 for the CeraSyl.

For the price and value, I really like Aqua Cera.

CeraSyl filters are currently $29 each. Here is a link.

4 CeraSyl filters are currently $99. Here is a link.

8 CeraSyl filters are currently $179. Here is a link.

Black CeraCarb filters are currently $39. Buy them at

St. Paul Mercantile also sells the whole canister system for $79 and up.

Just Water, Ceramic Drip Filter – A low cost choice is a Just Water, Ceramic Drip Water Filter from Monolithic Marketplace

These are water filters produced for the Texas Baptist Men’s organization that are used for disaster relief. It comes in a do-it-yourself kit where you use 2 of your own 5-gallon buckets to make the gravity drip system. It uses a single .5 micron silver impregnated ceramic filter with up to 1 gallon flow rate. Once in use the filter will last for 6-8 months. A Filter Specification Sheet is available at Detailed Assembly Instructions are available at The cost of the kit is $28. Filter only is $21. This is an item that can be given to neighbors to make them water self-sufficient so they don’t have to come to you.

The CeraSyl filter at only $8 more is a much better filter in my opinion.

Build Your Own – You can buy ready-made holding tanks and filter units or you can buy the ceramic filters separately and build your own system. Use the instruction links below to build your own system with two 5 gallon buckets and Berkey, Ceradyn or Aqua Cera filters.

Instructions to build a system are available at and

How Long Will You Need To Filter Water?
This is the $64 dollar question. Let me relay to you some facts from the 2001 Economic Collapse in Argentina as related by FerFal in his book “Surviving the Economic Collapse”.
Contrary to popular thought, the world does not end in an economic collapse. Life goes on, just more austere. Austerity applies to government as well as to individuals.

The local governments in Argentina, as part of cost cutting measures, started dumping large amounts of cheap chlorine into the water and sending it down the pipe into everyone’s house instead of processing municipal water as it used to do.
The water as it comes to the average Argentine home taste awful and is slowly poisoning the public. How long has this been going on? Since 2001, that is over 10 years. A $29 ceramic filter would remove the chlorine and other heavy metals as well as many other bad things in the water. Buying 8 CeraSyl filters for $179 would give you some great drinking water for 8 to 10 years.

I’ve run out of space so I’ll write “Water – Part 5” and finally write about the chemical treatment of water.


Ed Rogers

Copyright “Keep It Simple” 2012.  All Rights Reserved.

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