Fosse septique for cabin

Anyone know if I am allowed to build a wooden cabin/shed on my own land with a WC in it? I intend it to be about 16 sq metres, 2m tall and it will be made of wood… It will be more the two metres from any boundary and you would be hard pressed to see it from anywhere… I think my main issue is - can I install (get a professional to install) a very small fosse septique for this… It would be too far to hook it up to our existing fosse so thought maybe just give it one of its very own!! … A bit overkill for something that may be used once or twice a year… I cannot think of an alternative… really don’t fancy a composting toilet or anything that I have to empty myself… !! Fyi… usage is probably just a workshed… Many thanks…

At the very least you would have to submit a declaration préalable to your Mairie. If you put a fosse in, then it would need SPANC approval and the tax people would probably want to class it as residential

Do not do anything without the relevent permission and paperwork, it will come back and bite you on the arse bigtime otherwise. SPANC need to be consulted. Not being seen from the land, but the Impôts use drones and satelite imaging now to look at properties, hence all the pools being taxed now that were never declared or had permission for.

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Thanks guys - I wouldn’t do anything under the radar, but don’t want to do anything that is unnecessary either… Just trying to work out how to get what I want with as little admin as possible - dig a hole in the ground I think!!! I appreciate your responses…

It’s worth considering a composting toilet - they actually work really well and don’t create unpleasant odours at all.


That is really what you do not want when you are sitting on the toilet. :rofl: :rofl:

As always the Maire is your 1st port of call I would have thought.

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The size of the fosse is based on bedrooms I believe, regardless if they are used as bedrooms or not, well that’s what Monsieur Spanc told us. So we’ve twice the size fosse we really need, but at least we’re future proofed and the periods between emptying it should be decades :face_with_hand_over_mouth:

I’m not sure how SPANC would calculate the size required for your little shed and I’m not sure putting a “small” fosse would be that much cheaper. You have the same étude de sol, the same digger and a couple of blokes and probably not that much smaller épandage.

The minimum size fosse toutes eaux (not septique, those are no longer allowed) would be 3000 litres, which is mad for a workshop toilet.

A simple sawdust fed compost toilet is the way to go, & will save you a fortune, & avoid disruptive groundworks.

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