Apparently St John's conduit is currently in working order, having been painstakingly fixed on many occasions over the centuries since 1267, including very recently, so presumably there's a tap head somewhere in the church that could turn it on and give you a taste of water from the spring all the way up Park Street.
This is quite a feat of medieval engineering, as the pipes run both down and uphill in places, using a siphoning action to carry the water back uphill around the Pipe Street area (which is, indeed, named for the original water pipe.)
GPS Coordinates:
51.45623, -2.59497
Location: Old City