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The problem

the problem solution ocre ferreux

What is ferrous-based ochre?


Ferrous-based ochre is the result of a chemical reaction or biological process, both can occur individually or simultaneously:

Chemical reaction:when the ground contains iron, it migrates with the water towards the footing drain and when in contacts with air, it forms a muddy substance of iron hydroxide.

Biological process: when the iron-oxidizing bacterium is present in the groundwater, a gelatinous mass is produced following the oxidation of the iron in contact with the air.

When the biological process is added to the chemical reaction, the oxidation effect is considerably increased.

In both cases, the result is the formation of a viscous deposit on the walls of the grooved drain. It is this deposit that we call ferrous-based ochre. In the presence of water in the ground, the reduced iron oxidizes when it enters the drain, forming an iron hydroxide muddy substance that gradually blocks the drain (ref.: MAO)

In contact with the air, the ochre settles or is transformed into deposit

  • Orange-colored deposit, jelly-like, sticky and greasy
  • The ochre can crystallize and harden
  • Can form itself rather quickly and does not tend to resorb over time
  • Statistical case of advanced blockage after a 6-year period.

How does the ferrous-based ochre manifest itself?

The development of this matter is more likely to occur in airier ground, such as sandy grounds that contain silt, and less likely in grounds that are more clayey.

The chemical or biological reaction is also faster:

  • Where the ground is rather neutral (PH of about 7).
  • Where the footing drain is grooved.
  • Where the openings in the drain are punched instead of cut, which gives more grip for the deposits.
  • Where the drain is wrapped with a filtering membrane.

Under the action of the ferrous-based ochre, even the crushed gravel loses its filtering properties. The grounds rich in iron and in iron-oxidizing bacteria will produce iron deposits indefinitely.


Gallionelle • Leptothris • Sphaerotilus

What are the consequences of the presence of ferrous-based ochre?

Ferrous-based ochre causes several problems affecting buildings:

  • Reveals the deposits of ochre-colored sticky mud in rainwater collection ponds and ditches
  • Creates reddish deposits on concrete basements. These deposits release a sulfur-like smells.
  • Blocks agricultural drains: water from streams not being channeled away from the foundations, it infiltrates basements, at the junctions of the foundation walls and footing.
  • Blocks the backwater valves
  • Increases the humidity level inside the home, condensations in the windows, mould
  • Water damage in the basement from rainfall or thaw.