Septic Tanks / Fosses Septiques

Information Guide

  • Control Reports

There are two types of control reports carried out by the Service Public d'Assainissement Non Collectif (SPANC)

One is a periodic report, usually around 4year intervals. 

This report only tests if the system in place is working, it advises whether the fosse needs to be emptied.  It reports on what the installation is comprised of and most importantly, any pollution issues.  Just because you have a periodic report that says the system is working does not mean that the system conforms to French Regulations.

The second report is a report for when a house is to be sold. (Les diagnostiqueurs immobiliers-  since 1st January 2011 The seller is obliged to have this report)

This reports controls the conformity of the system, Checks the size of tank compared to the habitation size, checks that all the outlets go into the fosse tank, (not into rainwater drainage).  It checks what filter system you have after the fosse, either sand filter, land drains etc  It checks that the volume size of the filter compares  correctly to the habitation size of the house.  It checks the condition of the fosse (if access allows).

The report from this control will either part /fully pass/fail an existing installation.

The list of conditions will be included in this report. 

  • Obligations required if the Fosse installation does not conform

If you have purchased a house with a control report which does not conform, you have accepted this report as part of your legal package with the Notaire; you have an obligation to have the system brought up to conformity within the 1st year of ownership.  This dates back to all house purchased after the 1st January 2011.  The same applies to inheritance; children inheriting a property have to bring the system into conformity within the first year.

If you are selling a house with a fosse system that does not conform, your selling price can be negotiated to take this into account.  The buyer should be made aware that they need to calculate this work into the overall purchase and renovation budget.   However, new buyers coming into France are put off with the fear of administration or the thought of having the gardens etc dug up, this can reduce, not only the selling price, but the desirability of your property. 

  • How much?

This is a difficult question.  There are never two installations the same.  Each devis is prepared to individual needs, how many outlets, how deep do they need to be, how much land is there, can a traditional system be used or does it need to be a compact system.  What soil type, what ground levels, how high is the water table.  So many variants, until you have a visit from a qualified installer or bureau d'etude your system could be around 5/6000€ up to and over 8000€ before VAT

Always have a devis before budgeting to avoid over commitment financially. 

Stories of between 4 -5000€ are very rarely the reality. 

  • What are the different types of systems

Traditional systems will include a basic fosse tank, either polyethylene (P.E.) or concrete depending on your land type and position.  They start from 3000Ltr upwards. 

All your outlets from the house must connect into the fosse tank, these include washing machines, kitchen sinks etc 

If you have a cellar laundry room you may need a pump before the fosse if the outlets arrive below the manufactures maximum installation depth which determines the maximum depth of the pipes from the house to the fosse inlet.

After the fosse tank you need a filter system, either sand filter, drained or non-drained, land drains or you can find filter kits to reduce the volume size of a filter bed.  The type of soil, ground levels and environment will determine if or what traditional system will work best. 

The M³ of sand filter is calculated by the size of the property, in effect, the maximum anticipated number of occupants.  For land-drains (Epandage) the number of linear meters required is dependent on the size of property and the soil type and permeability.

Just because your friend has only 45ml for example your land may require 75ml for the same amount of bedrooms due to poor permeability.

If the outlet from the fosse to the filter system does not respect the required % fall you will need a pump station after the fosse to pump into the filter bed.  This is called a Poste de Relevage (clear water pump), it is after the primary treatment, ie the fosse septique tank.

If a pump is required to pump the house outlets to the fosse this is a Poste de Refoulement( a black water pump which is expensive)

Compact Systems

These are not micro stations, although often confused as one.  There are many compact filter systems, the main difference between them is most often, the filter media. 

The primary tank is the equivalent of the 'fosse septique' (septic tank) and works in the same way.

The second tank is the 'filter tank'.

There are many different types, some use rockwool cubes, some use coconut husk or hazelnut shells and one uses a mixture of polyethylene foams and grilles as the bacterial support.  The only must is be sure that the system you choose and install is one that has a French Agreement N°.  You may find the same system abroad cheaper but do not be tempted, the system will not pass a control without the correct agreement numbers.

Micro Stations

Micro-stations depend on a biological/bacterial action to clean the used water.  To this end they require a relatively constant use to 'feed' the bacteria.  This is why micro-stations are not acceptable for second/holiday homes as they simply will not work.

Although purchase and installation costs are comparable with other systems, it must be noted that ongoing costs are generally more expensive.  They do require electricity 24hours a day.  More importantly, they require emptying (vidange) more frequently, which is not an insignificant cost, on average around €200, some micro-stations require emptying every 9 months.

  • How to Proceed with a new installation

The first step is to find an installer that you feel confident with.  Check that they have adequate insurance to install septic tank systems.  This will be marked on their Assurance Attestation, the category to verify for installing Fosse systems is 1,5VRD Assainissement and Canalisations. 1,3 Terrassement Insurance is only for general ground works not for specialised Fosse Installation work. Check the insurance attestation is in current date.  You should always be given an example of the assurance with any devis.

Discuss with your chosen installer what type of system they would propose and how that would impact your environment.  Most qualified installers will have a good idea of what will or will not work for you.  If you sign with your preferred installer they will normally arrange the etude de sol on your behalf, or at least contact the bureau d'etudes outlining what type of system you have discussed and or chosen.  When comparing devis check for quality as well as price, check whether re-enforced CR4 or CR8 pipes are being used or just the basic N/F.  Verify if the discharge of the sub-soil is included, transport cost are very high if you have to arrange this privately.  Most installations will have from 15tonnes upwards to discharge off site. Check if the emptying and destruction of your existing tank is included.  Most importantly check that you have a 10 year insurance guarantee for the Fosse Installation.

Once you have chosen your system, possibly, your installer and obtained the Etude de Sol you need to complete and send an authorisation request dossier.  This is the Demand de Conception. Two copies need to be sent to your Mairie.  Again this is normally overseen by your installer if you have already chosen one.  No work may begin until an Avis Favorable from the SPANC is obtained.  This can take from 6weeks to 3months depending on Communes.

Finally once the installation is complete your installer will contact the SPANC and request a control of realisation before he back fills and closes the site.


Information Provided by      02 99 45 30 43




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