I just finished putting together a circuit, testing it and creating a video for an automatic bilge pump. This circuit can also be used to trigger a warning light or noise/sound.

Easy to build and inexpensive. The video shows the pump working. Enjoy!

Lew
Florida ☀️😎, USA

Pump (3-5V submersible) - I see the same on Amazon (2 for $7 US) the link below. Temu is even cheaper.

TIP120 Darlington available everywhere (~1$ US).

Tubing is 3/16 inch dia. (Tygon, aquarium, etc) .

Resistor 2K ohm I used a 2.2 K ohm (OK).

Breadboard - most anywhere electronics are sold.

Wires, small gauge. I used only black and red pairs to keep wires together.

Connectors - common small red battery type.

Plastic parts - If anyone has access to an FDM 3D printer, I can send you the STL files via email.

Lew
Florida, USA

https://www.amazon.com/Sipytoph-Submersible-Aquariums-Fountain-Hydroponics/dp/B09185Y8BN/ref=asc_df_B09185Y8BN/?gclid=CjwKCAjw17qvBhBrEiwA1rU9w9BCnY9ywNIukCOTarW3BMx_L1jBSaQyPHk0V0vppi1LBtQkPE_onBoCg30QAvD_BwE&hvadid=507755101118&hvdev=c&hvdvcmdl&hvlocint&hvlocphy=9012131&hvnetw=g&hvpone&hvpos&hvptwo&hvqmt&hvrand=496028437160920010&hvtargid=pla-1265514251177&linkCode=df0&mcid=2be73f49425435b3989b98b5fddaaa61&psc=1&tag=hyprod-20