Most of Europe uses a 460/230 split-phase transformer secondary with center tap of transformer as neutral connection which is also grounded at transformer. Neutral and a single side hot line is brought to residence. Your neighbor may get neutral to other hot end of transformer. In this configuration there should be no voltage between residential ground and neutral. For medium size users, like commercial stores and restaurants get both hots and neutral for full 460v/230v service, like U.S. but at twice the voltages.
You're getting confused by the peculiar American system - Europe (and most of the world) use three phase mains, not the American split-phase system.
So there are three lives and one neutral from the mains, and for domestic premises neutral and one live is provided, with alternate properties connected to alternate phases, to spread the load evenly, allowing a much thinner neutral cable then the lives. Commercial premises commonly have all three phases, required for large industrial machines (our small goods lift at work if three phase).
Certainly in the UK, and as far as I'm aware most countries?, the neutral is connected to earth at the transformer that drops the mains to 220/240 (depending on country, and nominally 230 in the EU) - and this is the basis of any kind of 'safety' from earthing appliances.
It sounds like the OP's pipes might not be earthed? - I would suggest checking from where the pipe (which obviously must be metal) actally enters the building - as there may be plastic piping inside, insulating where he tested to.
UK regulations require that
ALL metal pipes are earth bonded using suitably thick wire, but this only applies to new builds, or when upgrading (there's no requirement to modify old buildings).
Edit: A quick google shows that most of Norway has a floating mains supply, see IT Network here:
https://en.wikipedia.org/wiki/Earthing_system
Nasty!