We have air in our water lines. This all started after a check valve was put on right before the water pump (in the cellar...(shallow well, one line in). We have no leaks in the house, plumber rechecked any work he did for leaks, also replaced the old foot valve on the black hose down in the well, with a check valve. He said the pitless adapter was fine. By the way, the water pump check valve was put on because the water pump would kick on about every hour because it lost pressure. The check valve solved that problem but created the air in the lines problem. (the pressure in the water tank is fine). Also, the water in the lines happens when the water pump kicks on.