The presence of tannin adds another factor to the treatment of water.
Tannin is tannic acid, which is what tea is that we drink. When it rains in the woods, the water soaks into the leaves on the ground and creates tannic acid, which flows down through the soil into the well. If there is iron in the water, the tannin combines with iron, creating another element that prevents the iron from being filtered out. If the tannin is not removed, in spite of the oxidation created by ozone, there will still be a residual of iron after the filter. Removing tannin from the water after ozone oxidation will remove the color, the tannin and the residual iron.
Tannin resin is so expensive that it is sold by the ounce. Tannin resin can be added to a water softener tank so that both the hardness and calcium as well as the tannin can be removed at the same time. Most softener tanks are small, so adding tannin resin to an existing softener system usually requires a larger tank.
Some people do not like the slimy feel of softened water. If hard water is preferred, tannin resin can be used alone, without combining it with softening resin. Either way, the tank must be regenerated regularly with salt, and the backwash must operate routinely, usually once every two to four days. As long as the salt is added and the regeneration process is operating properly, the tannin resin can last indefinitely.
Adding labor, shipping, tax, and miscellaneous parts to the cost of the equipment, the approximate price is $2500.
Combined with a complete ozone system, the total could be $8000 for a typical household.
A smaller, slightly less expensive system can be sized for a single resident, for part-time use, or if the iron level is low.
When designing a water treatment system there are several variables:
labor hours, miscellaneous parts, tax, and whether or not additional parts are required, such as tannin removal, water softener, arsenic filter, pH stabilizer, etc. It is always best to have a water analysis done before ordering a system to determine the degree of contamination.