Rusty well water is caused when rainwater seeps through iron-rich rock and enters the aquifer. It can also be caused when the iron casing of the well or the water pipes in the well start to rust. Though the iron discolors the water, it is not necessarily unsafe to drink.
Problems arise because the water can stain laundry, plumbing fixtures and dishes. Iron can also accumulate to the point where it clogs the well pump, appliances dependent on water and garden sprinklers. It can give water a metallic taste and impart an off-taste to food and drinks. Too much iron can even turn some foods and drink black. Also, some bacteria use iron to proliferate.
There are several types of iron found in well water. Water that is clear when it comes out of the faucet but turns rust-colored later on is called clear water iron. Water that is rusty as it comes out of the faucet is ferric or red water iron. Organic iron can also be brown or yellow but may also be clear. Bacterial iron turns the water red and leaves slimy, rust colored deposits on pipes and fixtures. Though the bacteria are harmless, they impart noxious smells and tastes.