Yellow well water may be caused by iron deposits dissolving and entering into the well system from rain or melting snow. Yellow well water is also known as red-water iron, and it can also contain manganese. Bacteria in water pipes can also mix with iron and cause yellow water stains.
Organic iron is either yellow or red in color, and this common mineral sometimes seeps into wells that provide water to homes. To determine if iron is, in fact, the cause of the yellow tinge in the water supply requires testing. A laboratory can test water for iron levels and also test for the presence of iron bacteria. In general, yellow water from iron deposits contains small concentrations of iron. Low levels of iron from yellow-tinged water are not considered a health hazard. Even so, consuming large quantities of yellow water is not recommended.
Iron bacteria is also considered harmless to humans. However, iron and iron bacteria do tend to make the water taste metallic, making it unpleasant to drink. In addition, yellow water distorts the flavor of coffee, tea and foods. Eliminating red-water iron from well water usually requires water treatment with a carbon or sediment filter, which removes small amounts. An iron filtration system using either aeration or chemical oxidation is another option.