ᐅ Sewer Drain Slope – Can We Achieve the Required Gradient?

Hello,

I need some advice from people with experience.
We are planning to build a single-family house (without a basement) on a corner plot. The road running along the longer side of the plot (the plot is roughly rectangular, 21m by 34m (69 by 112 feet)) is slightly sloped. We want to orient the house towards this road because otherwise, with the house width, carport, etc., we wouldn’t fit, since we have to maintain a 5m (16 feet) setback at the street corner. Now we are considering how to best connect to the sewer system (the sewer runs roughly under the centerline of both streets) and I have several questions about this.

First of all: is it generally correct that connections are usually only possible or planned at the locations of manholes?
If yes, then theoretically two locations could work. One is about 12m (39 feet) from the house, and the other about 35m (115 feet). Of course, we would prefer to pay for fewer meters. However, the closer spot is on the slightly sloped road and is a bit higher than the position of the house on the plot. Now we wonder if the slope would still work for the connection. Unfortunately, I am not able to judge because, for example, I don’t know how high above the bottom of the sewer the connection pipe needs to be placed. According to a somewhat overwhelmed lady at the local authority, the sewer is approximately 2m (6.5 feet) deep.

Maybe someone here can help me a bit. I don’t know the exact height difference between the plot and the manhole, but it is definitely less than 1m (3.3 feet)... I would rather estimate about 50–60cm (20–24 inches).

Of course, we will discuss everything with the responsible authorities, but we’d like to get a rough idea first whether there is a chance to manage with fewer meters or if we definitely have to budget for high costs due to the longer distance.

Thanks in advance!

Hello,
usually you don’t have to align with the manholes. Get a sewer plan from your local authority. This will show all the necessary information, such as the exact point where the sewer connection is located on your property, as well as details like sewer depth, diameter, etc.
Regarding the slope, having a flat slope without a basement is generally not a problem. The mentioned connection point is at sewer depth. The slope to the connection is usually created on the last meters outside the house.

Good luck
Ippebson

Ippebson schrieb:
Hello,
you usually don’t need to base your plans on the manholes. Obtain a sewer map from your local authority. This will show all the necessary information, such as the exact location of the sewer connection on your property, as well as the sewer depth, diameter, and so on.
Regarding slope, with a flat site and no basement, it’s usually not an issue. The connection mentioned above is at sewer depth. The slope to the connection is generally created in the last few meters outside the building.

Good luck
Ippebson

Thank you! The problem is that when we asked the local authority for a sewer map, they gave us a plan that only shows the location of the sewer under the street and the manholes. There is nothing marked or indicated towards our property, and they claim they don’t have any other plans.

Yosan schrieb:
There is nothing marked or indicated towards our plot.

For a previously undeveloped plot, this is very likely because there simply isn’t anything there yet, right? You will need to install the appropriate inspection chambers (storm/sewage) on your property, which will then be connected to the main sewer system. This should work independently of any drains (gullies) on the street; otherwise, every house would have to be linked to an associated "street gully."

The slope from the house to your own inspection chamber should not be an issue, as this can be planned accordingly in advance.

Dr Hix schrieb:
For a previously undeveloped plot, it's very likely because nothing exists there yet, right? You will need to install the appropriate access points (stormwater/sewage) on your property, which then must be connected to the public sewer system. This should work independently of any access points (gullies) in the street; otherwise, every house would have its own associated "street gully."

The slope from the house to your own access point should not be a problem since it can be planned accordingly in advance.

Yes, that could be the case that nothing exists there yet. So, could the connection be made to any point on the sewer line, so we can simply take the shortest route? The gullies are marked on the plan with a circle and a cross, which, according to a friend of mine who should know because of her profession, are the designated connection points... I’m a bit confused now.

It is exactly as Dr. Hix describes: a maintenance shaft is installed on your property, with a straight branch leading from there to the pipe; this has nothing to do with a floor drain.