But we still have lots
of bugs in that water. How to get rid of them? Those bugs can be bad
news, and in this world there are lots of them. The days are gone when
you could walk up to a spring coming out of a mountain and simply drink
the water. Now, well, you understand. Most waterways now contain such
critters as coliforms of the fecal types, well known is E. Coli and
relatives, along with cryptosporidia and giardia lambdia (beaver fever)
and other less known nasty relatives, along with various viruses. These
little fellows, though they are small, account for a large percentage of
gastroenteritis and cryptosporidiosis, diseases that can be quite
debilitating.
Remember that pond
scum? Well, the bottom of that pond is loaded with little people
that prey on just such nasty critters. That's the natural remedy for
removal of harmful little bugs. So what we can do is to create a
perfect environment for the predators by making a place with slowly
seeping water, well oxygenated, and quiet enough to keep the critters in
there. Theoretically, then, we can use natural functions to make the
unnatural high concentrations of bad things go away.
It's called a slow
sand filter. While it is a simple and relatively inexpensive means to
purify water from biological contaminants, it is also quite effective:
more effective in fact than most of the house filters you can buy. For
instance, viruses range from approximately 10 to 1400 nanometers, or 10 to
1400 millionths of a millimeter, pretty small. The better house filters
will be micron filters, or one millionth of a meter, which is much larger
than the virus. House filters would therefore be ineffective against
viruses. The slow sand filter, however, keeps the water draining slowly
through a layer of biological predators whose livelihood is based on their
ability to eat such creatures as viruses, sporidia, giardia, and a host of
other fellows we don't want to drink. This layer of predators is called
the schmutzdecke.
A Tale of Two Cities
In 1892, an outbreak
of cholera occurred in Germany. Two cities involved in the study of the
outbreak were Hamburg and Altona. Both cities used the River Elbe as
their water source. Hamburg had 8605 deaths (1344 per 100,000), and
Altona recorded 328 deaths. A large percentage of the Altona deaths were
attributed to infections that occurred in Hamburg. So what was the
difference? The water in Hamburg was taken directly from the Elbe (yuck,
even then) while the water used in Altona was processed through a slow
sand filter. Does that convince everyone?
The World Health
Organization has endorsed the slow sand filter as the most practical
method for providing potable water for “third world countries.” But the
more interesting thing is that besides the Altona story, slow sand filters
have been used in major population centers worldwide, such as London and
Washington D.C. While these are no longer in use, the reason is not
because they don't work, it's because they are too slow and require a
large space. Other methods are now used, such as high pressure filtration
and chemical treatment. There is, however, renewed interest in slow sand
filters in smaller municipalities due to the much lower cost in both
construction and maintenance.
Since most of us don't
really like to have those strange chemicals in our water, there must be
other ways. Most municipal supplies use chlorine, a highly toxic
chemical, for bug killing, and also will add fluorides in one form or
another, presumably to protect teeth (questionable). We need to rid our
water of these, along with heavy metals and insecticides. This mandates
an addition to the biological filter, that being an activated carbon
filter.
Carbon filters will
remove the majority of nasty chemicals from your water. Activated carbon
granules are relatively inexpensive, and a home-brew filter can be
constructed using PVC.
So, you can take the
water from nearly any source within reason and put it through a plant of
your own construction, and have better water than virtually any municipal
supply. And you can do this for less than a couple hundred bucks. “But
wait, there's more!” If you are really an environmentalist, and truly
wish to make your footprint small, you can use slow sand filtration for
your sewage too! By using a slow sand filter for gray water, you'll
remove most pathogens from your household waste water, making the water
entirely safe for watering your garden (no viruses or other critters back
into the earth to nourish your garden), and you could reasonably use
another to process your black water, separately, making the water nearly
potable, believe it or not. Any test your county could run on either your
potable water or waste water would pass. The powers probably wouldn't let
you do black water, though, so we'll just call that a passing thought.
