Water has some special properties, making it a very unique substance.
There are three forces at work in this experiment: gravity, adhesion, and cohesion. Gravity pulls the water down toward Earth. Adhesion attracts water to other objects. Cohesion attracts water molecules to other water molecules. In this experiment adhesion attracts the water to the string and cohesion keeps the water flowing in a steady stream.
Water molecule has two hydrogen atoms and one oxygen atom. These atoms end up having positive and negative charges, which cause them to stick to one another. This is why you see raindrops clump together on your windshield when it rains and why it makes a stream of water as it flows down the string in this experiment!
At first, you soak the string in the water, and the water adheres to it. Even though water may drip out of it, it is still soaked in there. That is adhesion. When you pour water along it, you notice the water clings to other water molecules attached to the string, and you see it form a little stream underneath the string. That is cohesion!
Experiment with different distances. How far away can you get and still get the water to flow down the string? Let me know in the comments below how long your string was and what kind?