Tannin solutions are acids responsible for the color and some flavor in tea.
Tannin
Tanning oils are not bad for your skin, but are used for the wrong reasons sometimes. Tannin oil will not protect your skin in the sun and this can cause skin cancer in the future.
Tannic acid is a type of tannin that has a specific chemical structure, while tannin refers to a larger group of compounds found in plant tissues. Tannic acid is a more specific form of tannin with stronger astringent properties.
Tannin in coffee contains approximately 90,000 ppm. Tannin is also found in other products including red wines and apple cider.
Water
tannin
Foods that contain tannin include red wine, apple juice, apple cider, pears and red-skinned apples. Some people are sensitive to tannin and it can trigger migraines.
Other names for tannin include tannic acid, gallotannin, and gallotannic acid.
The chemical formula for tannin can vary depending on the specific type or source. However, in general, tannin is a complex mixture of polyphenolic compounds, predominantly composed of gallic acid units.
You probably mean Tannin. And there is normally no tannin in deep wells. Only in shallow wells.
Real tea, that is tea brewed from the Camellia sinensisplant, contains tannin because the leaves of the plant from which tea is made contains tannin. "Herbal teas" (also known as "tisanes"),made from infusions of fruits or herbs may or may not contain tannin depending the nature of plant used, but most seem to contain tannin and in some instances the amount is greater than that of real tea. Lemon grass 'tea' is a tasty herbal tea that does not contain tannin if it is 100% lemon grass.