But there are
alternatives. We can make our own filtration systems, and we can do it
for a fraction of the cost of a manufactured system, and have it be more
effective than many municipal treatment facilities. It's really quite
simple.
First, we remove the
turbidity, the cloudiness caused by various debris in the supply. This
can be as simple as a few layers of cloth, or as complex as a whole house
water filter. Since a whole house filter is quite costly, we go for a few
layers of coarse woven cloth, such as cheesecloth. This will remove most
of the large chunks of junk, and the rest we'll take out later. This step
may not be necessary with clear stream water, but it's a good idea
anyway. It's also possible to use the sediment filters available for RVs,
though those aren't terribly cheap either.
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.
