Tannins are a natural forming underground organic material that is found in many water wells. It is created from decayed organic matter and coal seams down in the water well. Water with tannins will be brownish or yellow in color, taste bitter, stain laundry, sinks, toilets, and tubs, as well as corrode chrome plumbing fixtures. The most effective way to remove tannins from water is to use Nano or Ultra Filtration Systems. An initial water test would need to be done to determine what pre-treatment would be required ahead of the Nano System. Tannin removal systems can be expensive but are very effective in most cases. Whole house Nano or Ultra Filtration systems work basically the same as whole house RO systems. The only difference is the type of membrane that is used.