Disclosed systems and methods relate to a water heater sensor for detecting a corrosion of an anode rod. According to embodiments, a system can include the anode rod in contact with water in a water heater, where the anode rod includes a corrodible sheath having a cavity. The system can include two electrical wires, where first ends of the two electrical wires, disposed within the cavity, are configured to come in contact with the water when the corrodible sheath of the anode rod corrodes to a certain point. The system can include a controller coupled to second ends of the two electrical wires, where the controller can detect whether the water is in contact with the first ends of the two electrical wires. The system can include an indicator to provide an indication when the water is in contact with the first ends of the two electrical wires.