Apartment block sharing my home's mains water connection

[lff12]

I don't understand what's stopping you from disconnecting/disabling the supply from your attic to the external apartments if you so choose? It's your attic.

Don't think its so simple. Its technically an easement, and should have been recorded in the legal work and survey. Its not uncommon for services for neighbours to run through another property's lands, but its unusual for it to be interconnected via the roof cavity.

 

[lff12]

So you bought a property with a large extension attached to it owned by a third party! This is pretty non-standard and your surveyor and solicitor should have raised some of the pitfalls here when you purchased.

Its technically called a back-to-back. These were commonly built 150-200 years ago esp in Yorkshire and Birmingham. They didn't have this issue with services when no such thing existed and one of the reasons most were knocked was because there wasn't space for plumbing.

You do actually see some in Dublin around East Wall, North Strand etc, but they are rare otherwise. I actually live in a modern one, an experimental set of 5 groups of 4x back-to-backs, where there is one on each corner. Because of their design tho, services are able to route (they are more like large split semi Ds).

 

[lff12]

Water supply is rarely detailed on planning docs.

Oh yes it is. Very much so.