Iron is a mineral that is essential for good health in certain doses. It finds its way into well water naturally or as a result of problems with the well construction or pipe system. In the former case, it is rarely present in dangerous levels, although a high iron content can affect the taste and appearance of water.
Iron is usually present in all water, although, according to the Wisconsin Department of Natural Resources, rarely in levels that exceed 10 milligrams per liter (mg/1) or 10 parts per million (ppm). The current recommended levels of iron in well water varies slightly by state, but they range between .2 and 1 mg/l. When iron exceeds these levels, the taste and color of the water can be affected, giving water a metallic flavor or odor and a red, brown or yellow cast that can stain dishes, laundry and fixtures.
Iron enters a well’s water supply in a number of ways, although the most common is by rainwater seeping through soil and picking up levels of soluble iron. It can also get into water as water runs through iron pipes in a plumbing system or as acids combine with naturally occurring iron in a shallow well or on the water's surface. High iron levels can attract iron bacteria, which consume the iron to survive. If you have iron bacteria, you may see a slimy, stinky brown to yellow residue in your sink, bathtub or toilet.
If you think you have high iron levels in your well water, you should first test the water for iron levels and determine the type of iron present. Testing kits are available for private well owners that will test for iron concentration, the presence of iron bacteria, pH, alkalinity and hardness. You will need to know these levels to determine the best course of treatment.
Lower, soluble iron concentrations, without the presence of bacteria, can be treated with filters or with phosphate additives placed in the well’s pressure tank. Zeolite softening agents will remove iron as well, although this can cause the iron to crystallize and accumulate in pipes. Serious iron problems can be treated with the installation of a manganese green-sand filter, which can remove both soluble and insoluble iron, although the filter must be cleaned and recharged periodically to remain effective. A bleach treatment will kill iron bacteria and can be used in conjunction with other treatments.