Expansion of wastewater sewer - What does such an extension cost per meter?

Hello everyone.

We are planning to purchase building plots, but we have a question regarding the sewer line that we have not been able to clarify so far.

First of all, about the plot in general:
These are two relatively old building plots in a very rural location. These plots are next to each other on a road and belong to the same owner. We want to build on plot 2 for various reasons (outskirts, etc.). For the "neighbor," the sewer line has already been extended to the middle of his plot. The previous owner only wants to sell both plots together. Due to the favorable prices, we would take both and try to sell plot 1 again as soon as possible. The colored marking roughly corresponds to the future position of the house.

About the problem:
As mentioned, the sewer line only goes as far as the neighbor. It would have to be extended for both plots. Now, of course, the question arises about the costs, as the extension would have to be made over a distance of about 70m where there is already a road.

Does anyone have experience with what such an extension of the sewer line would cost per meter? We would like to have a rough estimate since we currently have no idea. On the internet, mainly information about the costs from the house to the sewer can be found, which would be additional costs for us.

Another idea was to lay the sewer pipe from plot 2 along the road over plot 1 and only extend the sewer line to the beginning/middle of plot 1. That might be cheaper, and we could register everything in the land register since both plots would belong to us.

Do you have experience with this or tips on what else we should consider?

Thanks in advance and best regards
HaBaHa

Does anyone have experience with how much an extension of the sewer line would cost per meter?

The responsible authority knows that; usually, a phone call is enough to get a rough estimate. Since no one knows where you want to build, no one will be able to tell you what it costs.

Calculate with 500-1000 EUR per meter. That is the figure our wastewater utilities gave us and the upper end of which has actually proven true :-(

It becomes obvious why the properties are cheap (there is no other way to put it) or why the owner only wants to sell both together. The rear property is probably worthless without development.

Thanks to Traumfaenger for his helpful response. Meanwhile, we also have a statement of about €600-700 per meter from the utility company.