I think coding it so rain slowly fills up tubs would add an interesting option for tribal runs, especially in places with little water access. Imagine having to make a huge water collection depot in a desert.

Maybe as a balance point, tubs that are outside have a heightened chance to be dirty water. I mean, you are leaving tubs of sitting water out in the open after all.

(Also thanks again for this mod in general. Adds a lot of fun complexity to gameplay!)