Here is a tested Arduino project that uses 3 sensor probes as water level indicator with 3 leds and one LCD display + a simple controller that turns on a motor when the water has reached the desired ...

Automatic Water Tank Pump Switch Hardware • Microcontroller Unit: The designed circuit shown here includes an Atmega328P-PU as the kernel, a number of LEDs to display the system status, a push button ...

I was thinking there must be a simple sensor that could tell me when the water level has fallen a set amount and automatically run the "fill pool" zone on the Rachio.

Measuring water quality is a surprisingly complex endeavor as a result and often involves a wide array of sensors, much like this water quality meter from [RowlesGroupResearch].

The DIY shower monitor uses a flow sensor plumbed inline with a shower head, allowing it to transmit pulses to an Arduino full cost analysis and water usage.