ᐅ Use of lifting stations for the disposal of blackwater

Dear Forum Users

We are about to make a decision regarding the land and house purchase.

The canal bottom currently lies at 289.5 meters (948 feet).
The house, located 46 meters (151 feet) from the utility connection point, is planned to have the ground floor slab at 291 meters (954 feet).

To my understanding, a lifting station (sump pump system) is essential here. How can this be determined or calculated in detail?

Considering slope, frost depth, tolerance, and pipe diameter, I have theoretically estimated a required house elevation of 292.5 meters (959 feet) to avoid the need for a lifting station. Now I have also learned that the backflow level (flood level) must be taken into account.
How can this be determined and how should it be integrated or considered?

Thanks in advance. Best regards and thanks

The large online encyclopedia states: “The official backwater level is considered to be the road surface at the connection point of the property’s drainage sewer, unless otherwise specified by the responsible sewer authorities.”

Ronny1024 schrieb:

How can I determine this, or how should it be integrated or considered?

What suggestions has the house planner made? Then you don’t need to determine anything yourself, since the professional is paid for that. 😉

Ronny1024 schrieb:

We are about to make the decision to buy land and a house

The original poster probably wants to first check whether the plot, with all its conditions, is affordable for him...

Ronny1024 schrieb:

How can I determine this or how should it be integrated or taken into account?

This was also an issue during our house construction. The backwater level is the manhole cover plus 50 cm (20 inches). Our house is below the backwater level, so we installed a Staufix tank in the wastewater pipe. It protects against backflow with electronic valves but also pumps wastewater out of the house above the closed valves when necessary. This way, the house can still be used even if the valves are closed due to backflow. Of course, this needs to be approved in the drainage plan by the local authorities.

If I roughly calculate it, everything should also work without a lifting station in your case:
Channel invert level: 289.5 m (949 ft)
Ground floor of house: 291 m (955 ft)
Covering for frost protection: 0.8 m (31 inches)
Pipe diameter DN100 (approx. 4 inches): 0.1 m (4 inches)
Minimum slope for DN100: 1%
Distance from house to sewer: 46 m (151 feet)

291 m - 289.5 m - 0.8 m - 0.1 m = 0.6 m (So, 0.7 m (28 inches) of height is available for the wastewater pipe)
0.6 m / 46 m = 0.013 m/m or 1.3 cm/m (which corresponds to a 1.3% slope and is thus above the minimum slope)
291 m - 289.5 m = 1.5 m (the house is clearly above the required backwater level of 0.5 m (20 inches))

This estimate only works if drainage is done at the ground floor slab level and not somewhere in a basement that might not have been mentioned. The top edge of the pipe at the house is also 0.8 m (31 inches) below ground level. Depending on the location, additional cover may be necessary.

Thanks in advance for the information – I definitely want to avoid a pumping system for the main wastewater. It doesn’t matter for the washing machine in the basement, but I don’t want to have to pump rainwater (especially with the current extreme rain) or the water from the ground floor and upper floor.

That means I’m still looking for the highest possible manhole cover to raise it with… I’m already very, very grateful to all of you.

@Strahleman – thanks again for the info… Raising the house slightly might also be an option.