emergency water filtration

For those that have planned and prepared for acquiring and using alternative water sources, I know that you probably already have in your prep supplies a Katadyn water pump micro filter, or a Berkey or Berkey style gravity feed filtration system and Good for you. They will carry you and your family through most disasters.

For those of you that do not have (or are not familiar with) these new high tech ceramic style micro-filters, and would like to learn more, you will find links on our We Recommend Page.

emergency water filtrationThe only problem with those type systems is that, even though they are capable of producing anywhere from hundreds to thousands of gallons of potable water they are still limited by filter life which in a really long term survival scenario may not be long enough.

So for the sake of this article I intend to take us all the way back to the basics from emergency short term filtration methods (assuming we have no modern filtration methods at all) to proven long term filtration methods that work (and by long term I mean producing potable water with no additional purification needed, indefinitely).

Let’s begin with filtration since this is normally the first step in processing our alternative water sources. Depending on the quality of our alternative water source our first term we need to become familiar with is Turbidity.

Turbidity refers to the cloudiness or haziness of a fluid caused by suspended particles (such as algae’s or suspended solids in the fluid). These are usually large particles that can easily be removed by simple filtration or chemical reaction and sometimes just by allowing time to sit and separate (we will discuss how to reduce turbidity chemically later; you need to have the chemicals on hand to do this).

If you pour your alternative water source into a clear bottle and /or glass and cannot see through it, consider it to have a turbidity of 50% or greater. By the way those that have the Katadyn or Berkey filter systems the more you can reduce the turbidity prior to final filtering the longer your filter life.

Straining water from a questionable source is normally the first step to removing large particulates. This can be accomplished by pouring the water through materials such as coffee filters if available. If not available using 2 – 3 layers of fabric as a pre-filter will work just fine.

Settling is another simple method of removing large particulates from our questionable source. Many times just allowing milky or cloudy water enough time to set undisturbed ( 6 – 10 Hours ) it will settle itself.

This settling can be enhanced if you have access to clayey soil ( usually found at a soil depth of below 4″ in most areas ). Add about 1″ of this clayey soil for every 4″ of water in your bucket. Stir this combination until the soil is completely dissolved in the water.

Then allow it to set for those 6 – 10 hours. As the soil begins to settle to the bottom it will latch onto most of the other suspended particulates and hold them at the bottom. Just dip or siphon the clear water off the top being careful not to disturb the thick layer at the bottom of the bucket. Just remember the more we pre-filter this water the longer our final filtration filters will last.


Our First Emergency Water Filtration System

This simple emergency filter can be constructed from items found around the average home:

You need to find a 5 gal plastic bucket or metal can, a lightweight water tight kitchen style wastebasket or similar container. From the bottom make about a dozen holes within 2″ of the center using a #2 penny nail or close to that ( but nothing too large ). Cover the bottom with about 1″ to 2″ of washed pebbles or stones ( You can usually find theses being used as decoration in many flower beds or you can also use sticks or twisted wire coat hangers if necessary ).

Cover the stones with terrycloth, flannel, or other porous material ( cut up bath towels or flannel shirts that you have on hand ). Cut the material about 3″ larger that the container to allow some of the material to come up the sides.

Take soil containing some clay, in most areas soil from below 4″ deep will work. To Test squeeze the soil in your hand , it should form a ball, if poked with a finger it should break apart, if it does not form a ball the soil is to sandy and if it does not break apart when poked it has too much clay. Look elsewhere till you find the right mix. Compact the soil into layers over the first layer of cloth to a depth of approx. 6″ to 10″ deep.

Put another layer of terrycloth or flannel over the compacted soil and put stones on top to hold the cloth in place.

Support the filter can using sticks or boards above a larger collection tub such as a dish tub or roaster pan to collect the filtered water.

Slowly pour the contaminated water into your filter bucket. This system should deliver at first about 6 quarts of clear water per hour ( if filtration rate is more than 1 quart in 10 minutes, pull the top fabric and recompress the soil ).

After about 50 quarts this filter will slow to about 2 quarts per hour, at that point the soil will need to be changed and the top fabric will need to be rinsed and washed.

THIS WATER IS NOT READY FOR DRINKING AT THIS POINT, it is filtered not purified. It will need further purification before drinking, which we will explain later in the next article.


Long Term Water Solution no Purification Needed

The ultimate long term water solution is a demand slow sand filter. This method is currently being used by 3rd world countries worldwide and used for entire communities, implemented by the U.N. through the WHO ( World Health Organization ) and has been used by the U.S. itself for the past 200 years as a form of creating potable water for large communities, but can be scaled down to individual use.

The demand slow sand filter if set up properly is capable of producing ( when established ) all the potable water a family or even larger group can ever use without the needed addition of purification, indefinitely merely using a little periodic maintenance.

The demand slow sand filter sets up a biologically microbial layer that forms on the top layer of the sand and may take up to 10 days to 2 weeks to form ( prior to and during the 2 weeks period continue to use additional purification methods ), but once formed will filter suspended solids and suspended micro organisms, including parasites, bacteria and viruses that are captured on the filter surface. Parasite removal is near 100%. Initial bacteria capture is in the range of 60%.

Virus removal is believed to parallel that of bacteria removal. The rate of increase in the ability of the filter to remove bacteria increases with time (frequently several weeks according to testing) often approaching 100%; and is believed to be related to the rate of accumulation of organic material on the surface of the filter sand.

When an unacceptable flow rate begins a simple swish and dump procedure can reestablish flow rates required to continue flow of totally potable water. Plans and complete materials list for building a demand slow sand system will be made available on our site.

This is the ultimate solution to long term potable water without the need for dealing with the filter life limitations of modern ceramic filters.


When it comes to the End, I HIGHLY recommend a wonderful resource called “The Lost Ways” Check it out!


Video about emergency water filtration: