Water Level Sensor

The water cuts off sometimes where i live
so we have a tank on the roof
but sometimes the water cuts off for a long time and we use water but we don't know that it's from the tank
and each time the water cuts off i have to get on the roof and  remove tank cover to know how much water left
so i made this sensor to solve this problem
the idea is very easy.
Water conducts electricity poorly
so when the water reach the first sensor level , a 9v signal is sent to BC547 Base
and then the led glows.
i used a net cable and connector for the ease of use.
in my case, my tank is about 50cm high ,so i put a sensor about every 7cm.
The push button is very important for two reasons:
-Saving Battery
-and the most important reducing Ionization ,so the wires in the sensor part don't ruin

if you have any idea on improving it please leave a comment
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