What is Iron Ocher

 or Iron Bacteria…. commonly known as iron ocher, iron algae, or as some basement waterproofing installers call it, red slime or the “red stuff”. Actually the problem is not really iron ocher. Iron bacteria are microorganisms that use iron ocher as a source of energy. Here’s what basically happens in simple terms: First, one type of these microorganisms has the ability to attach itself to the side of a pump or the inside of a drainage pipe. They do so in order to feed on the nutrients that are flowing along in the water. Then what happens is other bacteria called iron bacteria are now able to attach themselves to these first organisms. They accumulate in jelly like masses creating what is called a biofilm. This biofilm if left untreated can clog pumps and drainage pipes.

If your sump pump and pipes look like this, you have an Iron Bacteria problem!

iron ocher 2iron oacher





A smell and an oil-like substance many times accompany the “red stuff”. It will appear as a rainbow colors on the surface of the water. The smell is because of the decomposed material. While iron bacteria are a nuisance, they are not harmful to humans. How would one know if they had a iron bacteria problem? Here are some clues:

  1. It seems that iron bacteria is more prevalent near a body of water such as along the coastline, a lake, pond or stream.
  2. It seems that it is more prevalent in silty sandy soil rather than hard clay.
  3. Red/orange staining of basement floor
  4. Red/orange staining at the end of a pump discharge.
  5. Oil-like substance on the surface of water in sump pit.
  6. Smell in the drainage water (decomposed materials)

Unfortunately, there are no methods to stop the proliferation of iron ocher and research on the matter has shown that the phenomenon can’t be eliminated. However, to prevent infiltration in the basement, the installation of maintenance chimneys have been used to periodically flush the foundation drain system. This approach does not solve the problem, but it has prevented the clogging of the foundation drain system. Click here to learn about sump pit and pump maintenance

Ref. Steve Andreas, Basement Health Organization