I've just been into the toilets at work and I noticed a earthing wire attached to a pipe. The pipe is a metal pipe that joins the cistern to the 4 urinals, the waste pipe for the urinals are plastic and the whole lot is screwed to a tiled wall.. the cistern is porcelain by the way...
Now am I right in thinking that the earth cable is a waste of time... (I must be really bored to notice such things...)