WE HAVE WATER!
Yesterday I connected the final section of copper piping leading from the expansion vessel in the loft to the kitchen. This morning I turned on the main tap, and inspected for leaks (there was one where the soldered joint had not been fully sealed, so I re-soldered it).
We now have clean borehole water all the way to the kitchen sink!
Next step is to fabricate a thermal store, and install the boiler stove. We’ll then have hot water too. What luxury!