A leveling device for determining the zero pressure point of an external draining system with respect to a patient is provided. The leveling device generally includes a body having a viewing element defining a field of vision, and a reference point indicator spaced apart from the viewing element and disposed within the line of vision. The viewing element and the reference point indicator define a line of sight. The device further includes a horizontal level indicator mated to the body and oriented parallel to the line of sight established by the viewing element and the reference point indicator. The horizontal level indicator is effective to indicate the horizontal alignment of the body with respect to a particular reference point viewed through the viewing element and indicated by the reference point indicator. The device can optionally include a reflector element disposed adjacent the horizontal level indicator and within the field of vision, such that the horizontal level indicator is visible through the viewing element via the reflector element.