Whether just tossed in or tethered, the Water-Rat Water-Level Sensor monitors water levels and sends real-time alerts via local cellular network to one's phone or PC any time the water level drops too low. Also, when the level rises, another alert is sent to inform that all is now OK. Everything required to do its job is inside this floating, cone-shaped device: an accelerometer tilt sensor (to detect movement), a NB-IoT chip (to send data), and GPS (to report location). And being portable, one Water-Rat can serve multiple tanks.