Geoscience Reference
In-Depth Information
source water, followed by a rinsing in filtered water, then laid out in the sun for further drying
and natural UV sterilization.
Caution:
The use of sari filters is not 100 percent safe. In controlled tests, the method re-
duced cholera infections by 52 percent, and a large number of mothers using sari filtration per-
ceived a significant decline in the incidence of diarrhea within their families. It is better than
nothing, but if you have other more sure-fire treatment options, I suggest you use them (Col-
well 2003).
Charcoal Filters
You can make your own crude charcoal filters to remove bad tastes, odors, and some pollutants
such as organic toxic chemicals and radioactive fallout. The easiest way to make charcoal is to
burn some wood and pick the bigger partially burned chunks out of the fire. Place these chunks
into a 5-gallon bucket and pour the water to be treated into the bucket. Shake vigorously for a
few seconds, then allow to stand for several minutes before filtering this water through a cloth,
sand filter, or coffee filter back into a suitable container. If toxic organic chemicals or radioact-
ive fallout are significant concerns, you should filter your water through at least 3 to 5 feet of
sand including two 3-inch-thick layers of charcoal. A 50-gallon drum filled with sand and char-
coal layers, with a few holes punched in the bottom, could do the job nicely. If you crush the
charcoal with some rocks, it will do a better job of filtering.
A more efficient way to make charcoal is with an old-fashioned charcoal kiln, which bakes
wood in a closed chamber above a fire. This process makes charcoal without burning the wood
sealed into the upper part of the kiln, since that section of the kiln does not allow enough oxy-
gen flow to support combustion. Another traditional method for making charcoal is by first
covering a huge pile of wood with a layer of straw or pine needles followed by a thick layer of
dirt, leaving a small chimney flue in the top center. Vent holes were scratched into the sides of
the dirt and the pine needles or straw were ignited through these vent holes. The chimney and
vent holes were partially covered to control the amount of air to ensure that the wood charred
into charcoal rather than burned into ash. The charcoal mound was watched carefully for sever-
al days, then the chimney and vent holes were completely plugged for several more until the
mound cooled down. If the mound keeper was not careful, the pile would build into a roaring
fire and burn all the wood to ashes (Wigginton 1979, 97-99).
If the need should ever arise, common household ion-exchange water softeners and carbon
or slow sand filters are particularly effective at removing radioactive materials from contamin-
ated water sources.
