I have to go with Speedy Petey on this one. As a journeyman electrician myself, I can tell you that you have created a very dangerous situation. Your water pipe is not to be used as a neutral, and that is what you are doing when you connect 70 volts to it. There should be 3 wires serving a house in your country, much like our country; except the 3rd wire is a ground. Do you have any 120 volt appliances in your home? A 70 volt return is like an open neutral on a 120 volt device. None the less, the 3rd wire on your service should handle this need. You should look towards your serving ground from the power company, because it sounds like it is failing. What you have done by hooking the ground to your water pipe is dangerous because when that fails, your water pipes will become electrified. It's the thought of standing in the shower soaking wet when that problem reoccurs that should make you worry. A water pipe can only carry current to ground efficiently for so long before it becomes corroded and fails. The idea of hooking a ground to a water pipe is only a safety measure in case a ground fault occurs.
Be careful what advice you follow out here, and good luck, my friend....
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