how to implement flowing of water

I’m trying to make 2D pipegame, (like pipe dream, pipe mania)
I finished most of the work. but I can’t find way to implement visualizing waterflow through pipe.

My first thought was doing it by using masking. But is doesnt seem to work with some backgrounds.
is there any other way to implement visualizing waterflow through piep?

For each pipe type, you should have an empty pipe sprite (non-animated) a filling-with-water animated sprite, and a full-of-flowing-water animated sprite.

That is simple and straightforward enough to implement; all you have is a substantial art drawing task ahead of you.