fosse septique

[amanda]

my problem concerns the fosse septique. at the moment when we use the bathroom sink or shower there is an emptying problem, ie very slow.

we have an observation hole in the garden in which I used to be able to see three inputs.

originally I had been able to determine that one is a direct input from the bathroom and the kitchen, the second is from the wc and the third from the sink in the lingerie/garage together with the garage roof gutter water.

the first and third inputs are immmediate in that when the sink is used there is an immediate flow of water observed into the observation chamber. the second, which is from the wc, has about a five minute delay, ie when you flush the wc, water appears very slowly after five minutes. does this indicate that the fosse tank is intercepting wc waste but not sink and shower waste? there is one output from this observation chamber, presumably to the dispersion area.

however nowadays there is head of water, about 0.5 to 1 meter above the inputs and outlet in the observation chamber. the problem is that there is a very slow flow of waste water out of the sink or shower base when the sink and or shower is used.

I wonder if the problem could relate to a full fosse or to a blocked dispersion field. I would be grateful if when answering this problem the reader would indicate if they are guessing or do write from expert knowledge. i would be grateful for either but obviously the latter would be prefered, thanks in advance.

[Gyn_Paul]

First of all, can you give us an idea of the length of pipe run from the WC you are talking about?

Are you sure this observation chamber (regard) is after the fosse and not before it?

Now a couple of observations:

If the water you observe coming from the different places is as you say then your fosse is not strictly allowed as these days a fosse toute eaux is required, i.e. one which treats not just the output from the WC, but also the bath, sinks, washing machine etc. But NOT the gutter rain water.

However I've not come across a system which unites the treated WC water with the grey water before, (well after, I suppose really!) perhaps others have.

If you are observing the flow post-fosse then 3 or 4 minutes is not - of itself - a long time, you are adding about 6 litres per flush to a volume of perhaps 1000 litres, so really the inertia of a body of water to give up 0.6%  is what you're looking at.

Nevertherless if things are running slow then either the pipes are blocked, or the tank needs emptying.

If the problem was in the dispersion field then te water would back up into the regard.

All in all, an interesting one!