Keeping Iron Bacteria out of Your Well

Are you one of almost 45 million Americans who get their water from a private well?1 If so, you undoubtedly want clean, safe, and clear water. But if unpleasant tastes or smells are coming out of your faucets, and your sinks, tubs, and toilets are stained reddish-brown, your well and water system might be contaminated with iron bacteria. This fall, one of us (RM) noticed a brownish foam in his toilet tank and a distinct iron taste to the drinking water, despite having an on-site water softener…

Iron bacteria-contaminated toilet tank
Photo credit: Thomas Scherer, North Dakota State University

Iron Bacteria and Well Water

Iron bacteria are microorganisms that use iron (or manganese) as an energy source. Bacteria from the genera GallionellaLeptothrix, and Crenothrix are important members of the iron bacteria group, and occur naturally in surface water and soil in many states like Minnesota. Whenever surface water or soil enters your well, these bacteria may be able to thrive in the plumbing of your home or business. Moreover, iron bacteria contamination can create a water quality environment suitable for disease-causing (pathogenic) bacteria, viruses, and other microbes. Although iron bacteria are not harmful, they can cause troublesome, persistent, and expensive well and related plumbing problems, including:

  • Unpleasant taste and odors resembling fuel, sewage, or rotten vegetation
  • Rusty, slime buildup in toilet tank, on filters, or the inside of the well casing
  • Oily sheen on the water surface
  • Reduced well production or efficiency of point-of-use treatment devices
  • Premature or excessive corrosion of well and plumbing components2

The characteristic reddish-brown slime or biofilm (biofouling) associated with iron bacteria contamination is a metabolic byproduct from the oxidation of iron or manganese by the bacteria. If left unchecked, biofouling can clog pump intakes, well screens, filters, and water pipes. The sometimes dramatic effects of iron bacteria can also be seen outdoors with reddish-brown slimy masses covering stream bottoms and lakeshores and the water having an oily sheen.

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1 President’s Council of Advisors on Science and Technology (2016). REPORT TO THE PRESIDENT: Science and Technology to Ensure the Safety of the Nation’s Drinking Water.

2 Iron Bacteria in Wells. Michigan DEQ Fact Sheet.