Q:
What are tannins and why is it important to know if I have tannins in my
water supply?
A:
Simply put, anything once alive can be considered organic. Tannins are
dissolved, decayed organic matter in the water, and generally not a health
risk. Tannins appear primarily in river or surface water and swamps, but, often
finds its way into wells through cracks and fissures
in rock formations. Most people drink a form of tannin every day in the guise
of tea or coffee.
Tannins will generally cause a yellow,
yellow/brownish tinge to the water. They come from decayed vegetation or animal
matter and is carbon-based as are all life forms. This
is significant because carbon tends to deplete oxygen and tannin-laden waters
will reduce the amount of free oxygen in water. This depletion of oxygen helps
explain how tannins contribute to the problem of acid water.
Tannins also prevent iron from being
oxidized and precipitated (process whereby iron is changed from a dissolved
form to a particle). Tannins in water are responsible for many failures
of iron removal filter systems and water softeners. Sometimes organic
matter will bind with heme iron (organic iron found
in hemoglobin*) and will cause the iron to pass through an
oxidation/precipitation process while remaining in dissolved form. The best way
to remove the iron in cases such as this is to treat the iron as an organic and
remove it with a tannin filter media.
Q:
How are tannins measured?
A:
There are so many variations of tannins that they are hard to define and
measure with standard testing. We have heard of estimates of 12,000 different
types of tannins. Some companies offer
Lignin Test Kits or more advanced labs have a T.O.C. (Total Organic Carbon)
test, but, neither test is foolproof.
An "eyeball test" for tannins
can be an effective way to estimate the amount of tannins in your water. First fill a white styrofoam cup with the water sample, leave it sit out
for 30 minutes, and then observe the color.
Tannin Concentration in Parts Per Million (PPM) Water color
0 - 0.5
Faint tinge of yellow
0.5 - 2.0 Darker
golden yellow (ginger ale)
2.0 - 3.0
Light tea color
3.0 - 5.0 Dark tea color
Q:
How does a tannin filter media (sometimes called organic scavenger)
work?
A: Would you believe no one has all the
answers to this question? Tannin filter media is made in many different
variations. Some work on an ion exchange principal, and some work through
adsorption. Some even work as a mechanical filter. Most tannin filter media
work using more than one method. WATERMARK LLC has tried a variety of tannin
filter media designs before choosing a system that gave us the best results in
field trials.
We designed our tannin removal systems
with an eye on why most other tannin systems fail. We use a tannin filter media
that works on all tannins in
*hemoglobin:
Any of numerous iron-containing respiratory pigments of red blood cells from
various organisms.