- Tannins are organic matter, sometimes found in water that give a light yellow to a dark tea color. This effect is caused by a variety of humic and fulvic organic acids, which are typically found in waters influenced by rainfall on hillsides, running off through natural soil and peats into streams, rivers and lakes. Tannins have also been found in deep groundwater wells.
- How do I know if I have tannins? Take a water sample in a clear glass or bottle and let it sit overnight. If the tea (brown) color remains in the sample then you can suspect that you have tannins. If the brown color drops out in the sample overnight then you have iron. Another test is to run cold water into a white 5-gallon bucket or into a white bathtub also letting it sit overnight. Tannins will not drop out of the solution and the sample will remain tea colored throughout. When in doubt, buy an inexpensive tannin test kit online (we do not offer).
- How to determine the sizing of a tannin system by using the following: The capacity per cubic foot of tannin selective anion resin regenerated with 10 pounds of salt is 2100 ppm of tannin.
Formula: 2100 divided by the ppm (parts per million) of tannins in your water equals the number of gallons per cubic foot of tannin resin.
- Example: 2100 divided by 10 ppm equals 210 gallons of water treated with one cubic foot of tannin resin.
- Note: Most people use an average of 75 gallons of water per day.
- Important: Water hardness of 10 grains or higher must be softened first and all iron must be removed ahead of a tannin removal system.