Water Level Indicator Circuit Using Bipolar Junction Transistor

Many circuits related to water level sensing/control are easily available on the internet, but the major drawback of all circuits which uses a metal probe as sensors is electrolysis. Electrolysis does not take place in circuits which uses a float switch or other sensors, but they are costly compared to circuits which use metal probes. Pure waters are bad conductors of electricity but unfortunately not all water we use are 100% pure. Moreover, in 100% pure water, water level sensing (which uses metal probes) does not work too!
Here is a simple water level indicator circuit with minimized electrolysis.