Martin Brown wrote:
On 22/09/2019 11:38, Graeme wrote:

Near here (Aberdeenshire), a fairly rough 1930s bungalow sold a while
ago, and was promptly demolished, to be replaced by a new detached
house.Â* Not a rural site as such, although a rural location, but a
road of similar houses, mains drains and electricity.

OK to answer the question the policy in Belgium is that all houses that
can are required to have a septic tank so that they only discharge
liquid effluent into the drains. Saves them having to dig out fat bergs.

Customer has to pay to have their own septic tank pumped out if they are
careless about what they throw down the toilet. The junk never makes it
into the main sewer saving a lot of hassle for the authorities.

Following completion of the house, a large hole was dug in the rear
garden, with a huge digger.Â* Somewhere between 2x3 to 3x4 meters (I'm
nosing through the fence).Â* The spoil was then sieved using the digger
bucket, the hole lined with plastic tarpaulins, and the stones from
the sieving put in the bottom.Â* I missed what happened next, but the
huge pile of sieved spoil has gone, as has the hole BUT there are two
corrugated pipes protruding from the ex hole, with manhole type lids.
There was a trench from the house to the hole.Â* I cannot think what
could be in the hole other than a septic tank, but why install a
septic tank with mains drainage outside, or what else could it be?
Not enough time elapsed to build a nuclear bunker!

It could also be a grey water tank for collecting rainwater off the roof
and drive. Our house in Belgium also had that refinement and I know a
few new builds where large tank rainwater collection has been added.

Why not ask the builder or owner?