A sensor system that measures at least one parameter of water includes an electronics subsystem and includes a sensor housing electrically and mechanically coupled to the electronics subsystem. The sensor housing encloses a chamber that receives water via at least one inlet and that releases water via at least one outlet. At least one sensor has at least one electrode exposed to water in the chamber. A flow generator causes water to flow through the chamber. A plurality of objects within the chamber move in response to the water flow and abrasively clean the at least one electrode. Preferably, the sensor system includes a chlorine sensor having at least two electrodes. The electronics subsystem applies a first differential voltage between the two electrodes during a measurement interval and then applies a second differential voltage between the two electrodes during an interval following the measurement interval.