Did you ever stop to think about How Do Bathroom Taps Work. Water is a fundamental human need. Each person on Earth requires at least 20 to 50 litres of clean, safe water a day for drinking, cooking, and simply keeping themselves clean”. The principle is very simple and affective. Taps are normally constructed from solid brass for a longer life and then chrome or gold plated to add an easy to clean finish. The water pipe is connected to the bottom. ¬†Water is then held in a chamber until required. When you want water all you need to do is turn the handle anticlockwise which unscrews an internal valve and starts the flow of ¬†the water.
Mixers taps work on the same principle but you do need a hot and a cold water supply connected and you will get cold, warm or hot mixed water depending on where you turn the handle.
This informative plumbing video shows a cut out of a brass kitchen tap and how its designed.