Earthed

Sinks, basins, radiators and pipe work should be earthed using an earth clamp and terminal connected via a yellow and green earth wire.
To earth metallic sinks, basins, baths and shower trays a 4 mm2 single-core earth wire should be used.
Earthing prevents faulty electrical wiring delivering a shock to anyone coming in contact with a live conductor reducing the risk
of electrocution.
'Electrocution' ,by the way, is a composite word derived from 'electro' and 'execution' coined at the time of the initial use of the electric chair as a mechanism of capital punishment. However since no English word was available for accidental deaths due to electricity the word 'electrocution' was adopted as a term for all deaths from the flow of current.

Many DIY enthusiasts undertake their own electrical wiring. But my advice is not to connect the pretty blue wire or the comforting looking brown wire to your pipes.
Just don't.