Geoscience Reference
In-Depth Information
According to Cresson Kearny, and testing at the Oak Ridge National Laboratory, simple earth
filters will remove about 98 percent of the radioactive fallout contamination from water, and
will do a better job of removing radioactive iodine than ion-exchange water softeners, boiling
water distillation, or carbon filtration. I personally believe that a good high-quality pressed-car-
bon block filter would do an excellent job of removing radioactive fallout particulates, but per-
haps this type of filter did not exist at the time that Kearny performed his tests back in the
1960s and 1970s. At any rate, Kearny describes how to build an effective homemade dirt filter
for removing fallout from drinking water as follows:
1. Perforate the bottom of a 5-gallon (20-liter) bucket, waterproof trash can, or similar container us-
ing a nail or drill.
2. Place a layer of clean pebbles or gravel about 1½ inches (4 cm) deep in the bottom of your con-
tainer.
3. Cover the pebbles with a layer of porous cloth, such as burlap or a piece of a towel. Cut the cloth
into a circular shape roughly 3 inches (8 cm) larger in diameter than the inside of the container.
4. Take soil containing some clay (nearly any soil will do) from at least 4 inches below the surface
of the ground (nearly all fallout particles remain at or near to the surface, unless they fell on sand
or gravel).
5. Pulverize the soil then gently press it in layers over the cloth that covers the pebbles, so that
the cloth is held snugly against the sides of the can. Do not use pure clay, since it is not porous
enough, or pure sand, since it is too porous. The soil in your bucket filter should be 6 to 7 inches
(15 to 18 cm) thick.
6. Completely cover the top of the soil with another layer of porous cloth, such as towel material.
This will keep the soil from eroding away when the water is poured into the filter, and the cloth
will pre-filter some of the coarser particles. A dozen small stones placed on top of the perimeter
of the cloth will help hold it in position.
7. Support the filter can on a rack of rods or sticks placed on top of a container to catch the filtered
water.
The contaminated water should be poured into the filter can, preferably after letting it settle
for a few hours to settle the largest particles to the bottom. As the filter flow rate starts to slow
down, you may boost its rate by removing the top cloth, rinsing it in water, and replacing the
top ½ inch (1 cm) of soil with new soil before putting the top cloth back into position. Eventu-
ally you will need to rebuild the filter with all new soil. Treat your water as usual (chlorine
bleach drops, boiling, carbon filter, etc.) to ensure that it has no harmful organisms residing in
it (Kearny 2006, 73).
If the threat of a nuclear disaster is keeping you up at night, I suggest you pick up a copy of
Cresson Kearny's classic
Nuclear War Survival Skills
, which is considered to be the definitive
