According to some embodiments, sewer alarm devices and apparatus are provided for detecting the presence of liquid within a pipe. In some embodiments, the devices and apparatus include a housing defining an interior volume, the housing including a top portion and a bottom portion, the bottom portion mounted on an exterior surface of the pipe. At least a first mounting portion extends outwardly from the housing and receives at least a first strap securing the housing to the exterior surface of the pipe. A probe housing extends from the interior volume of the housing to an interior of the pipe, and at least a first probe is disposed within the probe housing and exposed to the interior of the pipe along a first direction substantially along a center axis of the pipe.