Rabbit, rabbit!

Fosse Septic

It has been an extremely busy week. But as the weather has been superb and quite hot I have been able to progress and complete the Fosse.

This inspection chamber (Regard) has to be left open until it is inspected.


We have been extremely lucky with our requirements regarding the Fosse Septic.

The regulations are and having been going through a major overhaul and the local Mairie have a responsibility to ensure that all old Fosse Septics comply by 2006 (A hard task). Out of 4.5 million tanks in France, 3.5 million are thought not to comply.

In our case because we have a lot of ground around us and good drainage we have only needed to have a gravel drainage under the perforated pipe. Our neighbours were not so lucky and they had to have a sand filtration bed which proved very expensive.

How ours works.

The land is tested for permeability by an agency acting for the assainisement. Cost 600 euros


The evacuations reach a concrete Fosse which is buried under ground. The pipe work is a standard 100mm underground plastic solvent weld.


After it enters the chamber the effluent is digested by the bacteria (be sure not to use bleach or other chemicals that will destroy this).

When the levels reach the outfall the clean water is filtered off and is discharged to an inspection chamber (regard). In our case we have 4 outlets from the regard which exit level, for a minimum distance of 1 metre.


The water is then equally distributed over the four pipes which branch off laterally into black plastic perforated pipes which is encased in 20mm gravel (30mm under pipe with 20mm depth on top). A Geotextile membrane is rolled out over the gravel and top soil levelled over this.


Our requirement was for a minimum of 75 metre length of perforated pipe. There are many ways to do this but we opted to have 4 lengths of 20 metres each.