You have yourself a big aquarium! It contains precisely 100 litters of pure and fresh water. To ensure the perfect condition in the aquarium, you need to secure that the amount of water remains the exactly same. The math of it is pretty straightforward: on a daily basis one cup of water evaporates, so you need to poor one cup in.
Polluted content
It’s a simple, logic and foreseeable task. But what happens – you poor one cup of coffee in your aquarium on a daily basis. It takes only a few days before the small amount of coffee has polluted the complete content of your aquarium.
