What is biomat?

The biomat is a blackish and viscous substance which we find inside and around the drains of the field and on the crushedrocks-soil interface. The biomat consists of anaerobic bacteria (grow without oxygen) and molds and their by-products. It contributes to increase the degradation and filtration process by retaining particles, pathogens and virus present in the wastewater. But its outgrowth, also caused by the absence of oxygen over a long period of time, can bring the drain field to clog totally and more quickly than planned.

Can we control the biomat formation?


  1. By improving air diffusion through top soil
  2. By giving occasional respites to the drain field by reducing the water consumption
  3. By amending the microbiological matrix of the drain field on a regular basis.
  4. By having Urgence Septique inc.do periodical “backwash” of your drain field

Can Urgence Septique inc. bio-mechanical backwash remove the biomat?

Yes. A big part of the biomat is removed but not all. The biomat is necessary for a good wastewater treatment and for the protection of the ground water.

Is a clogged drain field inevitably obsolete?

No. If the cause of the septic system failure is not related to the water softener rinse water or due to any physical damages (roots, broken drains), we have all the good reasons to believe that the controlled pressure backwash of the drain field by Urgence Septique inc. will allow to restore it.

Can all clogged drain fields be restored?

No. As mentioned previously, a drain field damaged physically or by the water softener rinse water cannot be restored by the Urgence Septique inc. bio-mechanical technique.

How long does it take to do a controlled pressure backwash?

Approximately 4 hours.

Is the intervention going to damage my drain field?

No. We do not touch the drain field. The excavation required to do the intervention is localized at the far end of the septic tank.

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