Most red stains are a result of iron in the water. However, there are many types of iron, each calling for different methods of removal. A test will reveal what sort of iron problem your water has, so you can seek the appropriate treatment. If you see small red particles when you first run the water, this is usually a sign of oxidized iron. A fine mechanical filter is the best way to remove it. Or, the water can be chemically treated. Soluble iron forms rust particles after it contacts the air. If concentrations aren't too high, a water conditioner may do the trick; or you can use a water softener plus a filter. Another type is colloidal iron, tiny suspended particles that give the water a reddish tint. Chlorine and polymers are two common treatments. Yet another problem can arise from iron bacteria; these living organisms feed on the iron in water and plumbing fixtures, causing slimy growths. Large doses of chlorine are needed to kill the bacteria, and continual treatment may be necessary. Finally, there's organic bound iron. A carbon filter will often remove this form of iron. In severe cases, chlorine may be used. For more information on iron and red stains, consult a water conditioning company.