Water can be a lot more complicated than most
people think. For one, water is a universal solvent and a lot of things can be
dissolved by it. When water comes in contact with soil or rocks, like what
happens in natural aquifers or rivers, the water erodes away the topmost layers
of these rocks or that of the stream bed. This results in trace elements or
minerals in the water you use for bathing or drinking. If there is too much
mineral content in the water, it becomes hard water.