Disconnected Earth-Wire .. ?!?

Had to replace drainhose on my Dishwasher, and while I was behind the kickboard under the sink - which sits between the dishwasher and fridge - I found an earth-wire. One end was free, the other end disappeared behind the plaster panelling (modern house) and seemed to be attached - to what, I've no idea. The free-end looked as though it had never been attached to anything as it ended in a clean cut ie. copper core was not exposed.
Question:
For safety sake, should I simply connect this free end to the cold water pipe under the sink? ( - I'm guessing that was what the Sparky forgot to do when buidling the kitchen?). Am I likely to cause any electrical hazard in so doing? Or should I just leave/ignore it?
Any guidance appreciated from a qualified/experienced Electrician who KNOWS the correct answer! ;-)