Water is undoubtedly one of the main resources necessary for life to exist.
All living beings seek this resource. Water is present in the air, rivers, lakes, seas, and underground. It is estimated that 4.1% of all the water on the planet is below the ground, constituting one of the main strategic reserves of this resource. A good part of this resource is beneath our beloved Brazil: the Guarani Aquifer.
Water in the subsoil can be stored between the pores and empty spaces of soils, rocks, and sediments. This type of formation is called an aquifer. Water reaches these locations through rain, which infiltrates the soil and fills these spaces. By definition, an aquifer must be a geological formation that stores and transmits significant amounts of water. For this, the rock in the area must have sufficient porosity for the water to be stored. Additionally, the rock must have permeability to allow the 
liquid to transit and reach different points within the formation.
When a portion of the water from an aquifer is close to the surface and springs forth, a spring is created. The spring is a way for the aquifer to transmit its waters. Rivers can also be supplied by groundwater. Humans have learned to take advantage of these spectacular reserves through the construction of wells.
The water from aquifers is generally considered to be of good quality. The various layers of soil and rock through which rainwater passes act as a filter that retains impurities present in the rainwater, making it drinkable. Brazil is a very rich country in freshwater. Large rivers cross the country, supplying cities and providing life to living beings. Furthermore, it holds another immense wealth in its subsoil: the Guarani Aquifer.
Covering an area of 1,195,500 km², this gigantic formation spans four countries in South America: Brazil, Uruguay, 
Argentina, and Paraguay. Its largest portion is in Brazilian territory (70%), occupying areas in eight states: Mato Grosso do Sul (25.4%), Rio Grande do Sul (18.8%), São Paulo (18.6%), Paraná (15.6%), Goiás (6.5%), Minas Gerais (6.1%), Santa Catarina (5.9%), and Mato Grosso (3.1%).
The Guarani Aquifer began to form in the Mesozoic era, at the beginning of the Cretaceous period. The desert landscape that existed in the area was affected by intense volcanic activity. This deposited basaltic lava that eventually formed the rocks that make up the aquifer’s extent. Tectonic movements contributed to the emergence of the region, which for millions of years received and stored rainwater.
It is estimated that the volume of water stored in the Guarani Aquifer reaches 30,000 km³. This water is widely used by people living throughout its extent. Several medium and large cities use water from the aquifer to supply their inhabitants. Its extraction mainly occurs through the drilling of artesian wells, which bring the water to the surface for distribution.
Another use of the water occurs in agriculture. This is mainly for the irrigation of crops. The good quality of the water allows it to be used for this purpose, with the caveat of avoiding the irrigation of large crops to prevent reducing the aquifer’s volume. After all, the formation is replenished by rainwater, which slowly descends to the spaces in the rock.
All this wealth is under constant threat. Water waste is a factor that can deplete all the water in the aquifer. It may seem strange that so many millions of liters of water could run out one day. However, the unchecked consumption of an area that takes time to recharge, especially during dry periods, can lead to this outcome.
Misuse of the land is another constant threat. The Brazilian states that house the aquifer are major agricultural producers. Large areas of soybean, corn, coffee, and pasture crops are located above the water reserve, which can receive residues from 
pesticides and other products used indiscriminately in the fields. Soil contamination with oils, feces, and landfills will also send contaminating substances to the deeper regions of the soil, putting the quality of the aquifer’s water at risk. Concerned about this reality, Brazil, Argentina, Uruguay, and Paraguay signed an agreement for the rational use of the aquifer’s waters, promoting its conservation and proper use of this resource.
There is an urgent need for the rational use of the Guarani Aquifer’s water. Millions of people (not to mention other living beings in the region) need this water. To keep this resource available for many years, governmental agreements alone are not enough. A change in attitudes regarding water use is essential. Regions experiencing drought have had to adapt. It is not difficult. In fact, adaptation is one of nature’s greatest rules. Let us adapt to new realities, thinking about the distant (or near, as you prefer) future. But let it be a future with quality water for all.
Source: www.eurekabrasil.com, by Túlio Lima Botelho