Fosse septique - etude de filieres

[Postie]

We asked a local company to do a survey for a new fosse at the house we have just bought, stating specifically that we need a system to cater for a 3 bedroom house. We bought the house with four bedrooms (one downstairs which we will turn into the kitchen). The dossier has come back with facilities catering for 4 bedrooms & thus a 4000 ltr tank not a 3000 ltr tank. Will this be a big issue when the time comes to install the system and should we ask for the dossier to be changed? We will be installing the system ourselves.

Thanx Postie

[thunderhorse]

I think there's often some misunderstanding between bedrooms/fosse size. What size fosse for 10 bedrooms - all en-suite - but only ever two occupants? The figures I've seen are approx. 275+ litres of water per person per day - then multiply by 3 (3 days for the water to run through the fosse.) So four people: 4 x 275 x 3 = 3300 litres minimum (or 4000).

How companies (are obliged to) work it out, I don't know, but it does seem that sometimes their common sense is lacking. However, there's surely some advantage in erring on the larger side.

Hope that helps a bit.

[gosub]

I doubt if there is a big price difference between the 3000l and 4000l tank, the groundwork / pipework difference is negligible 3000l is the legal minimum anyway, so I would go for the larger system.

[Dave&Olive]

[quote user="thunderhorse"]I think there's often some misunderstanding between bedrooms/fosse size. What size fosse for 10 bedrooms - all en-suite - but only ever two occupants? The figures I've seen are approx. 275+ litres of water per person per day - then multiply by 3 (3 days for the water to run through the fosse.) So four people: 4 x 275 x 3 = 3300 litres minimum (or 4000).

How companies (are obliged to) work it out, I don't know, but it does seem that sometimes their common sense is lacking. However, there's surely some advantage in erring on the larger side.

Hope that helps a bit.
[/quote]

 hi ok

         this above should be 145 lts per person ..... so 145 X 6 persons (for a three bed house )  X 3 days stock as said above =2700 ltrs

a 4000 ltr tank are much  more expensive ,you will not find them in the brico`s ... but the expense comes if you have to have a sand filter..3000ltr tank needs a 25 m3    4000 ltr needs  35m3 one .

if you take a look at my  photobucket you will see a 25m3 sand filter 

 Dave

[Postie]

Hi & thanx to all who replied.

Dave, I have checked & you are right with your calculations. And yes, 3000 ltr tank is 445Euros & a 4000 ltr tank is 790Euros. The price of the sand for a 3000ltr tank is about 600Euros & for a 4000ltr tank about 1400Euros. Total difference is about 1145Euros (109%) this is a calculated guess so it could be worse!!![:'(].  Anyway, after much thought, I have decided to write to the company who did the survey & ask for an amendment to their dossier. I will wait & see what I get back from them. Renovating a house is not cheap & if we save 1000 Euros on one thing it just means we can get on & do the next thing. I sure don't want to be in a position where the money runs out before the job is done!!!

Postie

[Dave&Olive]

hi ok

 why go back for a devis if you are going to do the job yourself ?? go to S.V.L  and they will come out for free tell you what you want etc and will supply you with the doc`s after

 if you need more info email me

         Dave

[Lilly]

As far as I am aware it is the SVL that will tell you what size of fosse to have as there are rules that if you have a four bedroom /10 bedroom house it has to accomodate the amount of people that could actually be using the house not the amount of people that are currently using it and remember you will need to get a certificate of conformatity from them so it pays to get the calculation right as well as what drainage and where it is to be situated. We found the Fosse/ water authorities to be very helpfull in guidance for installation so if you are doing the work yourself they would be your best bet in contacting them not a contractor.

[Postie]

Hi Dave, we aren't getting a devis - just an amendment to the Etudie de Filieres (which is wrong!) that we have already paid for. I want the survey to be correct so when we actually do the job it conforms to their specifications. I will email you or call you tomorrow. Thanx for your help - it's worth a jug or two down at the local!!!

Darryl

[Ron Avery]

Postie. Look at the post from Lilly above.  Its spot on.   If you contact your Mairie the SVL, its called SPANC here, will do an inspection and give you a report detailing the type of fosse and size of fosse needed, the size is related to existing bedrooms. 

Here in 12 if you call them to do the inspection,  it is free.  If they turn up to check your fosse is up to the new standards, you pay for the inspection and report, other departments arrangements may vary.  Either way if you have a fosse installed or do it yourself, it cannot be commissioned until inspected by SPANC and if its not to the spec they detailed,  it will not be commissioned and then fines will be applied.

[Postie]

Hi Ron

Thanx for the reply. We did in fact go to our Mairie's office who gave us the lowdown on the requirements for our area. We were given a list of companies who do the Etude de Filieres & we chose one of them. Their fee for this very detailed study was 350euros. Our water company also sent out a man (SPANC) to inspect our existing fosse and give their reccomendations, this cost us 29.90euros (obilgatory in this area!). They will also inspect our new installation for free & commision it when it's done to their satisfaction. The house we bought is a 3 bedroomed house with an single storey extension that was used as bedroom by an elderly relative. Because we will change this room into the kitchen long before we install the new fosse I can't see that there will be a problem. The house will be a 3 bed house at the time of the new installation!