Methods and systems monitor a state of a fluid-distribution system. Sensors are distributed spatially within the fluid-distribution system. Each sensor is in peer-to-peer communication with another sensor to define a dynamically networked arrangement of sensors within the fluid-distribution system. The sensors have an illumination source, a light detector, and a controller to measure a photometric parameter. A base station is provided in communication with the sensors to access the networked arrangement of sensors. A central system is provided in communication with the base station and has programming instructions to identify an abnormality in the fluid-distribution system from data collected by the sensors.