Moving downstairs toilet advice (Is this feasible or not practical at all)

Hello, I'm looking to make my downstairs area open plan but don't want to sacrifice the downstairs toilet if possible. I want to move the toilet to be under the stairs, which is about 4m away from the current soil pipe (Soil pipe from bathroom above current location, house is end of Terrence with bathroom/soil pipe on next doors house side rather than outside.).


The floor is concrete so would need to have a channel cut out for the 4m soil pipe and pipework for sink etc. Is this distance not practical / not feasible at all?

Just looking for some advice before I seriously start approaching contractors for the job

Thanks in advance!

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@Venox need those plans.
Hpw are you proposing to connect to the soil/sewer at the lower end of the run?
Is it deep enough to give you the required fall from the new wc position?

@dilalio my bad, attached images.

That is a good point, i'll lookup and calculate the required run depth. The current soil pipe is hidden away in the wall, I'll have to see if there's a way to find out how deep the soil pipe goes into the concrete floor before heading to the sewer in my garden.