I know posts on automated plant care are very popular on Gadget Master, so I want to highlight this Arduino appnote - Smart Farm Irrigation System Using Arduino Edge Control.

The Arduino Plant Watering System is designed to automatically supply water to your plant's soil once its moisture level falls below a particular point. The system relies on two key components to ...

If the system starts running low on water, the Arduino triggers the valve on his spigot to open, keeping the water level above the pump inlet pipe.