Are the connections of a demolition property usable?

Back again to the usability of the connections: We have the same situation and at least our water supplier said that we actually save something if we do not apply for a new connection, but rather a relocation with temporary deactivation for the demolition and after the construction again a relocation and activation of the deactivated connection ...

The house has a basement. The lady at the building authority told me it would make sense to use it for a new house. What should I pay attention to besides the basement being dry?

For example, whether the basement is usable: smaller than the planned house is not necessarily a problem, but if it partly lies outside the desired house footprint, it is. Or the standing height may be sufficient now, but only for a raised ground-floor "first floor", and you want to build at ground level. "Lady at the building authority" and "real estate agent" initially sound to laypeople like "more knowledgeable than oneself," but that does not necessarily have to be the case.

Thank you very much for all the tips, but the matter has been settled today. The property will not be it.