Well-water problem

Iron in well water: test the form before choosing the filter

Orange stains can come from dissolved ferrous iron, oxidized ferric iron or iron bacteria. Each behaves differently, so treatment should follow the test result—not the stain color alone.

Three common iron problems

Ferrous iron is dissolved and may look clear at first, then turn orange after exposure to air. Ferric iron is already oxidized and appears as visible rust particles. Iron bacteria can create slime, odor and fouling and may require disinfection as well as filtration.

What to test

At minimum, test total iron, manganese, pH, hardness and other relevant well-water chemistry. If slime or biological activity is suspected, include appropriate bacteria testing.

Treatment logic

Low dissolved iron can sometimes be handled by ion exchange when hardness is also present. Higher iron levels often need oxidation followed by filtration. Ferric iron may benefit from sediment removal. Iron bacteria can require shock disinfection or ongoing disinfection depending on the source and severity.

Do not size by stain color: treatment capacity depends on concentration, pH, flow, oxidant demand and the presence of manganese or sulfur.