This is for Indian/Pakistani chapati recipe.  How do I know if I have used the appropriate amount of water when making the dough? There is no yeast involved here. What do I do if I have added too much water?  When I made the dough for first time in life a few days ago, I tried to use 2:1 ratio of flour to water. However, all water was not used making flour have higher ratio. Quite a bit of water was left when I finished. It is hard to accurately say what % was left.  Even after leaving it for more than an hour, when I started making the chapatis, the dough was too much sticky and I think this is because of adding more water than needed. 
It can be used as an egg substitute in various baking applications; search with the keyword "aquafaba" to learn more about this.  Also, it is used as a thickener in some bean-based dishes (eg common in chana masala).  Also, it can be used as stock for some types of soups.  Since you describe the juice as brown, it seems that you are cooking dark coloured beans like black or kidney beans; the same usages apply but might be limited by the unwanted color.  The same usages apply to bean juice from canned beans.  Mind that bean juices do have the same (or even stronger) flatulence-inducing effects that beans have. 