As far as I knew, the builder provided everything within your sites boundary, but the local authority provides the 'actual connection' to their mains water (similar with sewer connections) for a set fee.
If this has changed then surely there is a specialist sub-contractor the council recommends for such work, as an ordinary builder couldn't (read wouldn't want to) be held liable for things like cracks to public pavements which can be exposed years later and ultimately be attributed to his work on that water connection.