All soil is made up of basically three different things – sand, silt, and clay. The different soils found around the United States include different combinations of these three things.
For our earthen water filter we’re looking for a high clay content soil.
Clay binds to radioactive particles. If radioactive fallout has contaminated the water supplies, earth filters utilizing clay type soil, will effectively remove the radioactive particles from the water.
According to the American Civil Defense Association, this method is better than distillation, ion-exchange filters, or charcoal filters for this purpose.
How to make an earthen water filter for radioactive water
1. Perforate the bottom of a 5-gallon can or wastebasket with holes punched within 2 inches of the center.
2. Place a two-inch layer of washed pebbles on the bottom of the can.
3. Cover the pebbles with one thickness of terry cloth towel or other porous cloth.
4. Scrape the top 4-5 inches of soil off the ground to get below the fallout, and dig enough clay-type soil to fill the can to a depth of 8 inches, packing it tightly against the sides.
5. Cover the soil in the can with another thickness of toweling and another one or two inches of pebbles.
6. Suspend the can over a clean container and pour the contaminated water into the top.
Clear (but unpurified) water will come out the bottom at the rate of about 6 quarts per hour.
Replace and discard the clay soil after approximately 10-gallons of filtered water.
Remember to purify the water afterwards by boiling or other acceptable methods.
Does my soil have clay in it?
While clay soil (especially heavy clay) can be challenging to work with for gardening, it is very effective for using in an earthen water filter to remove radioactive particles. You may wonder if the soil where you live has clay in it…
The following maps show where in the United States there is some clay in the soil.
Definition of clay soil…
Soil which is composed of very fine particles, usually silicates of aluminum and/or iron and magnesium. Clay soil impedes the flow of water, meaning it absorbs water slowly and then retains it for a long time. Wet clay soil is heavy and sticky, and tends to swell from the added moisture. When dry, clay soil shrinks and settles. The top layer can bake into a hard, concrete-like crust which cracks. Some plants have difficulty growing in clay soil because their seedlings or roots are unable to penetrate through hard, dry soil, or can be waterlogged in wet soil. Adding organic material to clay soil is an effective method of improving growing conditions.
Just because the maps above may not include your geographical area does not mean that there is no clay around… Most of us have encountered clay at one time or another in our lives and since you probably know what it looks and feels like, you will know it when you see it (or dig for it).