Could some explain how to make water on a buttercream cake.

I want to make a beach scene with sand & water..

Iv heard people say something with piping jel.
Do you just mix the piping jel & color then pour on the cake?

Thank you again 4 your help

Yes you made do that. I prefer to use a spatula.

I made a waterfall cake and used regular marshmallow fluff, put a touch of color in it, and you are off and running. It works pretty easily. and looks cool too.