What’s all the fosse? A guide to septic tanks

What’s all the fosse? A guide to septic tanks

The fosse septique is one of those less glamorous intricacies of French life that could take you unawares. Mary Hall explains how to prepare for buying homes with a septic tank

Agreeing a sale and arranging to go to the notaire is an exciting time for buyers and sellers alike. There’s so much to think about all at once that it can be hard to concentrate on what really matters: the terms of the sale contract, commonly known as the compromis de vente. This binds buyers and it must be read and understood fully before proceeding any further. The buyer then has the benefit of a seven-day cooling off period during which he/she can reconsider terms and pull out without penalty, but the vendor isn’t so lucky.

For properties not on mains drainage one of the most important pieces of paper in the bundle of diagnostic reports is the one on the state of the foul drainage system. I know of several agents who request the report as soon as they take on a mandate to sell a house, so that they know exactly what any problems may be, or indeed to promote the fact that everything is hunkydory in the fosse department.

If an installation is sub-standard, their professional attitude enables them to advise vendors to get works done, or to discuss what would be an appropriate reduction in price when a sale is being negotiated. Sadly this isn’t always the case, and all too often there’s chaos at the notaire’s when all sides are trying to make out what needs doing and at what cost. Non-French speakers may feel overwhelmed and either party may be rushed into making a rash decision with a nasty impact on their wallet.


The vendor is legally obliged to provide a formal report on the condition of their non-mains drainage facilities, prepared by the local inspecting body. The report must be no more than three years old when the sale goes through. The report will detail what is in place where, with a plan, and how well it has been maintained. It may conclude that the system:

• conforms: great!

• partially conforms: certain works required

• does not conform: alarm bells

• is non-existent: either the toilets drain into the wild or the inspector couldn’t find any evidence of a system

• causes a risk to the environment or to health: this must be sorted ASAP.

When a property is sold, if the vendor hasn’t brought the drainage up to standard, the new owner has to fix any problems within one year of purchase. With a completely new system potentially costing around €10,000, depending on the size of the property and local ground conditions, you can see it’s very important to know exactly where you stand.


If you haven’t got a recent report on your system, ask for a new inspection as soon as you decide to sell so that you know what your position is. A positive report is a good marketing tool. If the system doesn’t conform you can work out what you want to do so that you are in control of subsequent sale negotiations. It makes sense to do small jobs such as emptying the fosse or cleaning out the bac à graisse (grease trap) if that’s required, and to mend broken pipes.

If neither you nor the inspector know where anything is, it’s worth trying to find out. Get in touch with a local terrassier (specialist digger), or if you’ve used a reliable local builder he may have some ideas. Proving where your fosse is and that it’s OK could save you thousands.

A common problem is proving the existence of the post-fosse filtration area (filière de traitement). As recently as 12 years ago, many installers didn’t put in visible manholes at the entry and exit points, so inspectors are bound to conclude that one doesn’t exist if they can’t actually see it.

If your system is relatively recent it’s worth contacting the installer to see if they can remember the details as it could cost as little as €400 for him to pop along, dig down and put in a couple of manholes. Then you ask the inspector to come back to look at it and bingo. You should have a 100% OK report to smooth your sale along.

In some older properties, the outfall from the fosse goes to a soakaway (puisard or puits perdu). This is no longer acceptable and a filtration area will need to be created. The size and type will depend on ground conditions, your boundaries and the existence of any water sources and watercourses. The inspector will be able to tell you what he wants. You can then obtain quotes from contractors, and decide whether to get the work done, or present the quotes as a sale reduction offer.


If you’re presented with a report saying work needs to be done, you’ll want to know how much it’s going to cost you to put it right, and to negotiate the purchase price accordingly.

You may want the vendor to fix the problem, so that when you move in there’s nothing to do. On the other hand, if you’re planning to put in a pool or create a patio, or extend the property it may well be to your advantage to take on the liability to do the work, so that you can control where everything goes. The last thing you want is a brand new fosse just where you planned to sit under your rose trellis.

If you’re buying a place with no proof of any system at all, the best advice is to assume the worst and go for a major price reduction and argue from there. If the vendor insists there is a system and that it works, it’s up to him to prove it, not you.

One special case I dealt with recently concerned an old cottage on a very small plot of land. The vendor and agent were totally honest about the fact that waste water disappeared into the ground in the old-fashioned way. They weren’t being so clear about the feasibility and cost of a new system on such a constrained plot. The buyer was head over heels in love with the place, but luckily he took his rose-tinted glasses off long enough to contact me. I made a few calls, as a result of which he was able to get appropriate tightly worded clauses suspensives written into the compromis de vente, leaving his dream intact and his budget under control.

CASE STUDY: a light-hearted tale of Bev and Paul Sexton’s new fosse septique

Pipedream or precise plan, the decision to take the leap into the unknown is a daunting prospect, even for the more intrepid ones among us. We chose to move to France firstly because Paul is half-French and he wanted to see whether he was more French than English, and also because we wanted to give our son, Harry, the marvellous opportunity to be bilingual.

It was on a weekend visit to friends near St-Lô that we spotted our first home. Arriving in France, just off the ferry, we purchased some flowers for our friends and just happened to park in front of an estate agency, where we briefly glanced at the array of properties in the window and were impressed at what we could get for our money.

The following day we decided to return to St-Lô and after lunch and a few glasses of wine in a local brasserie, we weighed up the fors and againsts of moving to France. It was then that we plucked up the courage to enter the world of the French immobilier.

After a long meeting with the agent we chose three houses to visit. The visits proved very interesting as it became apparent very soon that what you saw in the photos was not what you got in reality. Unfinished properties were prevalent, where one room looked amazing but the next was back to basics with plasterboard walls, or ‘placco’ as they call it here, and dodgy wiring.

Another viewing trip almost ended with a visit to casualty when the door in a bedroom actually opened out to a 20-foot drop. Eventually, after viewing 17 houses, we decided on a property and the compromis was signed after Paul had negotiated the best price possible.

Three months later we were saying our goodbyes to family and friends to start our new life in Normandy. Our new home, a former B&B, was in a lovely location overlooking fishing lakes with stunning views of the surrounding countryside, a haven of peace and tranquility.

After a few days of arranging our belongings, Paul decided that he should get the fosse septique emptied. It is an age-old saying isn’t it, ‘you don’t know what you’ve got till it’s gone’. Well, that is what fosses septiques mean to me.

The septic tank seems a thing of the past in the UK, but not here in France unless you are living in the towns and cities.

Our first encounter with our fosse was rather unusual as we could not find it, there was no evidence of it on the house plans and our gravelled drive and lawn area showed no visible signs of it either. After locating pipes leaving the house we decided to call the local fosse emptier, hoping he would have an expert knowledge of where it was situated.

He duly arrived and I hoped that he did not notice my look of horror as I shook his hand and then suddenly realised where his hands had been (no gloves used, I hasten to add).

Paul explained our dilemma and the guy looked equally confused. He paced around the gravelled drive at the front of the house, rubbing his chin and then gave the usual Gallic shrug of the shoulders. Suddenly, a flash of inspiration registered and he proceeded to make a call from his mobile phone. After a considerable amount of gesticulation and shrugs and strange-sounding French (which later turned out to be the local patois, or local dialect) he explained that he had a friend who was in possession of a small digger.

He arranged for his mate to come to the house along with the digger with the intention of doing a bit of excavation work in the attempt to find our fosse. I gave Paul a rather pained look and said, “I’ll leave you to it,” before hastily retreating into the house.

The next time I ventured outside, the drive resembled a building site with a three-foot trench running along the side of the house. Paul smiled painfully and said, with encouragement, “I think they’ve found the fosse. We just have to do an experiment.”

“What kind of experiment?” I asked somewhat pensively.

“Well,” he said, “we have to flush all of the loos in the house at the same time to see which pipe the water runs out of.”

Seeing as we had five loos in the house I was looking forward to seeing how we could perform a synchronised flush with just two people. Amazingly, it was achieved with the help of Monsieur Fosse Emptier and his son who had arrived to join the party.

About five hours after these shenanigans started the fosse was eventually emptied and I had shaken the hand, yet again, of the man who empties septic tanks and does not wear gloves while doing so.

Later that evening, while sipping a chilled glass of rosé on our patio, I casually said to Paul, “Well that was an unexpected sort of day. I wouldn’t want too many of those to come along. I didn’t think then that I would be eating my words, but that’s for another time!”

Mary Hall is a property manager

Tel: 0033 (0)5 65 24 66 46

[email protected]

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