What are Tannins?
Tannins
are a natural organic material that can be the byproducts of nature’s
fermentation process, be created as water passes through peaty soil and
decaying vegetation. This can cause water to have a faint yellow to tea-like color,
and can cause yellow staining on fabrics, fixtures, china and laundry.
Tannins
may give a tangy or tart aftertaste to water. They may also cause water to have
a musty or earthy odor.
Tannins
– also known as fulvic or humic acid – are more common in surface water
supplies and shallow wells than in deep wells.
Water
in marshy, low-lying, or coastal areas is also more susceptible to tannins.
What are the health effects of
Tannins?
Tannins
are considered an aesthetic problem. While they may make water unappealing to
drink and stain laundry, they present no health hazard.
Should I test my water for Tannins?
Tannins
create a light yellow to dark brown discoloration in the water.
A
simple test for tannins involves filling a clear glass with water and letting it
sit overnight. If the color settles to the bottom of the glass, the
discoloration is most likely caused by iron and/or manganese and not tannins.
If
the intensity of the color remains intact, it is most likely caused by tannins.
You
may also wish to test for sulfates, alkalinity, iron, total dissolved solids
(TDS) and hardness, as these may help determine which treatment method(s) will
be most effective for your situation.
There
is another reason to test for iron along with tannins; iron creates a false
positive for tannins and must be subtracted from the tannin result to determine
that true tannin concentration.
What can I use to remove Tannins
from my water?
Common
tannin treatment uses an organic scavenging anion exchange resin. Organic
scavenging units use anion exchange resins. These resins “trade” negatively charged
ions for tannins in the water.
The
anion resin is sensitive to hardness, so most systems include a water softener
as pretreatment. The water softener extends the life of the anion resin and
increases tannin absorption.
Anion
exchange resin systems should be regenerated occasionally with a baking soda
and salt water solution to improve the effectiveness of the resin.
When
cleaning is needed, the water will have a “fishy” odor caused by the fouled
anion resin.
Anion
exchange resin systems can also change the chloride, alkalinity and sulfate
levels of the water, so you may wish to monitor these substances more closely
once the system is installed.
Oxidation
and filtration is another method to remove tannins, but is not as simple as
anion exchange and softening. Contact a water treatment expert in your area for
assistance.
It
should be noted that tannins can sometimes interfere with equipment used to
treat other water problems. For example, the resins or medias in iron filters,
cation exchange filters and neutralizing filters can become coated by the
tannins, and may no longer work properly.
It
may be useful to test for tannins (using the “clear glass” method described
above) before installing these types of water treatment devices.
Related Posts:
https://www.watersystemscouncil.org/download/wellcare_information_sheets/potential_groundwater_contaminant_information_sheets/96111501_Tannins.pdf
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