its been my long dream to build this but budget limit on building big high concrete tank. the idea is like this. 2 sensors (assume normally LO if no water) to activate deactivate water pump on the ground. 1 sensor (SENS1) = full (pump stop if HI got water), 1 sensor (SENS2) = need refill positioned somewhere in the middle (pump ON if LO aka no water) think hysterisis. i bought the sensors in ebay china long time ago, plenty of variety there, but since i have no tank, hence no project only dream. the code is simple as ABC, pseudo...
do {
if (SENS1 == HI) motor = OFF;
else if (SENS2 == LO) motor = ON;
};
ps: darn its hard to key in TAB in this editor