Iron bacteria are living organisms that feed on the iron found in the water, pipes, fittings, etc. They build slime all along the water flow path. Occasionally, the slimy growths break free, causing extremely discolored water. If a large slug breaks loose, it can pass through to the point of use, plugging fixtures. These types of bacteria are becoming more common throughout the United States. If you suspect bacteria iron, look for a reddish or green slime buildup in your toilet flush tank. To confirm your suspicions, gather a sample of this slime and take it to your local health department, or water department for observation under the microscope. This type of iron problem is very hard to eliminate. You must kill the bacteria, usually by chlorination. You must use high amounts of chlorine throughout your plumbing system to kill all organisms. You may find it necessary to feed chlorine continuously to prevent re-growth. A filter alone will not solve this problem.