Earth to stop cock bonding

[houseofzane]

At the side of my house I have a lean too and many years ago my Dad installed all the electrics. He added an additional bit of work that was going to be a single socket for a heater but we decided on not having a heater in the room so he put a fuse spur socket on it.
I was wondering as this isn’t being used if I could remove the section now but I’m not sure if I can. The cable comes from my consumer unit and goes to the fuse spur. But he also ran an earth cable from my stop cock to the fuse spur.
I know you need your water bonded but I already have 1 earth to it so was wondering if this second one could be removed or is it just a waste of time and leave it as it is. Unfortunately my Dad is no longer around to ask.
Just after a bit of advice on this really

 

[ebee]

But he also ran an earth cable from my stop cock to the fuse spur.

Can you draw us a diagram showing the cable, the stop cock and pipework (is it metal or plastic) and the fused connection unit (I assume that is what you are describing as a "fuse spur") please, thanks. I am trying to establish if this is a main stop cock for the house or a separate one purely for the lean too but connected to the same pipework running underground and therefore requiring bonding so instead he has run an earthwire as an equalising conductor. Thanks.

 

[houseofzane]

The pipework is all metal and it’s linked to the main stopcock in the house. Yes it’s a fused connection unit that he told me we could swap to a single socket if I wanted

 

[ebee]

Yes, it sounds like he took the precaution of adding that earthwire as an equalising conductor to reduce risks. Essentially, in simple terms. to ensure the earth as presented at the socket, connection unit or appliance will always be at the same polarity as the pipework .
That might sound odd but in all installations we try to ensure that anything that is "earthed" is always at the same electrical potential, so the ground beneat our feet and the metal case of an appliance is always at the same (or almost the same) voltage , any doubt that it always will be is mitigated by the addition of an equalising conductor, it is known as bonding, we bond all things together, electrically, to make them substantially at the same polarity.
He probably decided that despite it should really be main bonding requiring say running a 10.0mm earth cable from the house earth bar to the water stop cock it should, in practice, be sufficient to run a supplementary earthwire from the socket/FCU earth to the stopcock.
In reality it probably would do so if it is substantial enough for those limited purposes. If not and you stood barefoot (and maybe wet) on the stopcock or connected pipework and the metal case of an appliance or socket at the same time you could get an electric shock from the differences of voltage between them, if they are both connected by a conductor then that should reduce that voltage to nearly zero therefore safe to touch both at the same time.
Like I said it should really be connected by a big thick cable but (without actually seeing it) I would probably not be too worried about it and all other things being equal so to speak it is probably doing no harm and might be doing some good.