Connect the ends of the water pipes.

On the left side of the screen you can see what pipe sections are available. These are given randomly by the system. The flashing dot indicates which one is coming. On the right indicates where the fluid is.

As soon as it reaches the course, the water will appear at the pipe ends marked with a flashing dot.

Tap the track where you want to place the current pipe section.
Until the liquid gets into one section of pipe, you can replace it with another. Just touch it.

You can speed up the water flow rate with the icon in the lower left corner. Only touch if you have already connected the pipe ends.