I recently made a post on the Live/Neutral crossed wiring I found on a
kitchen socket. I am awaiting on a socket tester before I carry on to
correct the socket if need be.

Today I was looking at another socket which has it's own seperate circuit
back to the fusebox and is also located in the kitchen but on the opposite
side. The earth wire doesn't go back to the fusebox but to a copper pipe. I
followed the pipe and found another earth connector further along where the
earth wire connects to another socket. This socket belongs to a 2nd
circuit which has an earth cable going back to the fusebox.

My question is, should each circuit have an earth cable go back to the
consumer fusebox or can it be done like above?