A self-charging sensor (SCS) adapted for use in a toilet or the like. The SCS includes a housing having a rechargeable battery; a turbine module having a multilevel impeller having offset wheels that are adapted to be driven by a fluid flow via an inlet port during an event, wherein a rotation of the impeller causes the turbine module to generate electricity that recharges the rechargeable battery; and a processing module that collects count data associated with the rotation during the event; and an attachment component adapted to seat the housing on an overflow tube.