the system includes structure for supporting at least one tube within a pipe . the tube has one end disposed close to , or in contact with , a wall of the pipe . a sensor is disposed within the at least one tube to detect a pressure gradient or fluid movement within the tube . such pressure gradient or fluid movement indicates a leak in the pipe adjacent to the tube location . in a preferred embodiment , the structure is a ring sized to fit within the pipe and the ring supports a plurality of tubes . in another aspect , the tube includes a restriction to prevent flow and pressure is measured on each side of the restriction .