How do I make sprites follow a player-created path?

I'm making a pipe rotation game. I have the mechanics for snapping the pipes into place and rotating the pipes down. I was hoping to add animation of water droplets traveling along the pipes. My question is how do I get the water droplet sprite to follow the path of pipes the player has created?

The pathfinding behavior really only works for avoiding solid objects, not following a variable route. Does anyone have any suggestions of how I could do this? Thanks!

Did you find a solution? I am trying to do something similar only all I need to do is find out if the path is connected. Any ideas?

The paths in this kind of game are usually simple (basically straights and well defined turns), you could have Image Points for each pipe to guide the water. Since (I'm guessing) this is a linear structure you would just move the water drops from one Image Point to the next in progression.