Water is undoubtedly the most important natural resource on the planet. This is well known. But what many people probably do not know is that it is essentially a recyclable resource, rather than a renewable one such as wood. The fact that it is recyclable means that in the closed earth-atmosphere system, the quantity of water and its reserves remain the same at all times. Therefore, we cannot look forward to an increase. In contrast to this, the earth’s population has been rising steadily from historical times to the present, and for the last two centuries at a particularly rapid pace. Therefore, we have a pair, the pair “water-earth population”, in which the first part’s price remains theoretically stable, while the second one’s price is rising, creating thus a great inequality in the supply and demand array. From this alone, it can be understood why today and in the future, irrespective of the much-discussed phenomenon of “climate change,” the water resource will be in a continuous and growing shortage.