Unconventional Switch: Water

This circuit, powered by the Circuit Playground Express, demonstrates how water can be used as a system for a switch. Using only a breadboard, a blue LED, a bowl of heavily salted water, and clips to connect everything together, the circuit won't light up without the metal probes both being submerged in water, which makes it an indication of whether or not water is present up to a certain level.

While there are limitations based on available materials, such as the placement of the probes or how brightly the LED is glowing, with stronger, industrial voltages to combat water's naturally high resistance and without the need to salt the water, this circuit exemplifies how commercial and residential water systems can be made to include indicators for water in terms of safety and if there is a need to add to an empty container.