Consider something simpler made from just switches.
From each switch lever, suspend a float on a fixed length thread/light chain. When the water is high enough, the float releases the switch. When water is too low, the weight of the float activates the switch. This kind of design has the advantage that all the electrical parts are above water; also it's easy to test: you push the switches manually and make sure all your signals work as desired. (I'm not entirely sure what exact functionality you want from your ladder drawing.)
If you use two pole switches, you can organise your indicators completely independently of your pump lockout. You can get switches which are okay for mains. Or if you want to keep them completely isolated, you could use a relay.
simulate this circuit – Schematic created using CircuitLab
Alternatively, you could use magnets with reed relays, but I'd expect the microswitch with lever and float/weight is simplest.
Typical Switches and Floats
Frm ZF Switches
From Plastech