The water cycle and its purifying function

Precipitation → Mountain → Rivers → Ocean

Water is in constant circulation and, whether in the sea or rivers, it never stays in the same place. The radiation emitted by the sun heats and evaporates the waters of the oceans and on the Earth's surface, which, transformed into clouds, precipitate in the form of rain or snow. This precipitation flows through the rivers, which conduct the water back to the sea, beginning a new cycle. It is through this uninterrupted process that saltwater from the sea is desalinated during evaporation, creating an essential resource for our life on Earth: freshwater.

In the vast cycle that carries water from sea to sky, from sky to earth, and then from land to sea, the forests located in the upper portion of a watershed play a crucial role, especially in a country with dense forest cover like Japan. Forests, mainly due to the action of their soil, have the ability to absorb rainwater and let it drain gradually. This not only contributes to flood control and river volume stability, but also acts in water purification. The water that flows through the forest soil carries few impurities, contains balanced minerals and has a pH close to neutral.

In the path of the rainwater that permeates the forest, being absorbed by the soil and emerging in a watercourse, the substances that cause eutrophication, that is, water pollution by excess nutrients such as phosphorus and nitrogen, are neutralized, as they are retained in the soil absorbed by vegetation. At the same time, a number of other minerals dissolve in balanced proportions. This process as a whole gives the water that passes through the forest soil a higher quality, so that it can be used in agricultural and industrial practices and for consumption. 

Main minerals contained in Japan's Water

Calcium

Sodium

Potassium

Magnesium