Just recently we are hearing loud banging noises coming from the kitchen upstairs. This noise sometimes sounds like someone lightly banging on the wall to a very loud thump that actually shakes the glassware on the counter. The water is never in use when this happens, it is heard at different hours during the day and night it and sometimes it is not heard for a few days. What could be causing this noise? We have our own well and septic the house is 19 years old.