Assainissement/fosse septique/toilette sèche à combustion

Hello everyone. I'm a new member. I would like some advice. We live in the Champagne-Ardenne and have one habitable house and one collapsing old cottage. We moved here nearly a year ago. We are trying to decide what to do with the old cottage. We have already had part of it demolished (at some expense) because we considered it a hazard to the public. We would like to try and save the rest of the house (if only because to demolish it and remove the rubble would cost a great deal.) The cottage has a fosse septique i.e. cess pit, of which SPANC says the following: "....Les eaux ménagères ne sont pas traitées. Système de traitement est en charge (présence de terre dans le regard de répartition). Travaux majeurs à réaliser dans l'année: Réhabilitation complète du système s'assainissement non collectif ......." I do not want to approach SPANC at this stage for advice as I do not want to alert them to the fact that we have not carried out the required work yet. (We cannot afford to do so until we sell our previous house, which is unlikely to be soon, in view of the current market). The Maire is aware of the state of the cottage, as we sought his advice before demolishing part of it. He did not give us the impression that he would suddenly order us to do the work, or be fined. At the moment the cottage would be used (when habitable) as a maison d'amis, although that could change at some time in the future and become lived-in full time. The Maire said a new system of assainissement would cost around €15 000. I think he had in a mind a microstation. We do not want to spend that sort of money when re-roofing alone could be in the region of €40 000, without the extensive repairs needed to the stone walls.

I have seen a toilette sèche à combustion on the internet and it looks to me a very interesting concept (link here: At €3 620,00 it's not cheap but it can be installed almost anywhere in a house. My question: is it possible/permissable to have one or two of these toilets and have the household waste water from baths, basins, washing machines etc. flow into the existing (cleaned out) fosse septique? Does "grey" water have to be treated, as does faecal matter? If it is possible it would save us the expense and not inconsiderable hassle of replacing the whole system. Although our property has 7000 sq.metres of land, the cottage is close to the road. I do not particularly want to install a microstation, which I don't think is suitable for occasional use anyway. Our habitable house has a (conforming) fosse toutes eaux with a filtre à sable vertical drainé and we have had no problems with it and we would not object to one of those for the cottage, space permitting.

Sorry for the long message, but the more information, the better someone can understand our problem. Thanks in advance for any replies.

Hello Jane. Thanks for your reply (and the replies from both Johns). The Maire was just giving an approximate cost whilst we were chatting generally about the state of the cottage. It does seem rather high but we have not yet tried getting estimates. John, it is too soon to ask SPANC to advise. We need to know the overall cost of renovating the propery. There is no point in installing a new septic tank to a property that is going to be pulled down. My question was: does household waste water (everything apart from the waste products from toilets) have to be treated? Could the existing cess pit be kept just for household water and the excrement handled by a combustion toilet? (The latter is environmentally friendly, as it burns urine as well as faeces and doesn't use water at all to operate). I suspect the answer is no, the cess pit must be replaced with a fosse septique toutes eaux, but I am curious to know the answer. The cess pit itself is in good order and could function again if cleaned out. Thanks everyone.

I think that you need to talk to SPANC, that way you will get the correct information.


I followed a lead on this thread. Compared to the silence, quarter replies from other enquiries the response was full and helpful

Hello Jenny,

I live in pas de calais and am about to have my third fosse septic installed in as many moves, in a few months time.

We have opted for a micro station having heard great reviews and recommendations. However our quote is considerably less at just under €9,000 (suitable up to 6 people). The most we ever paid for a fosse with the new regulations was €13,500 as indeed most of our friends paid.

Hope this information helps.