Question

What happen when electricity is passed through tap water

Answer 1

Then the water gets electricity and if we touch it we will get shock

Answer 2

    Tap water contains a lot of impurities minerals salts which are easily ionizable. So they conduct electricity when dissolved in water. So tap water is a very good conductor of electricity. 

   So people who touch the tap water get an electric shock immediately. It is dangerous. So the taps should in general be insulated well from electric connections.