As someone else said, that voltage does not represent wasted electricity; it
represents DANGER. If the ground wire at one of your outlets is 70 volts
above true ground, then when you grab onto the exterior case of an appliance
such as a washing machine, you may be grabbing onto something that is 70
volts above ground and can shock you.

It sounds like some kind of ground connection is missing. Time to have the
electrician in. This does not sound like a major repair, but it needs to be
done by someone who can take a good look around and make sure everything is
connected right.