You already know the rivers, the streams, the lakes and the springs.
Today we show you what an aquifer is.

An aquifer is a permeable geological formation
that stores a lot of usable water.

A geological formation is the shape of the land, are soil layers that have the same characteristics.
For example, it can be sand or rock, among other materials.
A permeable material is a material that lets water or other liquid pass through its composition, such as pores or holes.

Water from aquifers is also called groundwater.
It is water located below the ground or the Earth's surface.
The geological formations that create aquifers, were formed over many years and centuries.
The aquifers are filled with the water that falls and passes through the earth, then goes through several layers of rock and soil, until it reaches the area where it accumulates.
Water from aquifers can come out through springs.
Water springs are also called water eyes.
There are two types of groundwater: springs and wells.
In a spring, the water comes out naturally.
In a well, you have to drill the soil to get the water out, and sometimes it is necessary to pump to use water.

Figure 1. Images of a well and a spring.

Another type of aquifers is the shallow one.
Shallow one means that the water is closer to the surface.
Deep drilling is not required in these aquifers.
There are artisan wells that we draw water using a bucket and a loop.
In many parts of the country, aquifers have been overexploited, which means we have drawn more water than the water that they receive.

In other cases, aquifers are contaminated
by harmful substances or particles that were dragged by surface water on its way from the surface to below the ground.
That contaminated water reaches the aquifer.

For example, aquifers are contaminated by:

• Chemical residues used in agriculture
• Parasites and microorganisms that live in the sewage, and drain over the surface or through rivers.

That's why it's important to collect contaminated water and clean it in treatment plants.
This way we do not contaminate our aquifers.
Many cities and towns use water from aquifers, surface water from rivers, streams and lakes is insufficient to supply cities, produce food and other products.

It's hard to know the amount and quality of water in an aquifer.
It is very important to conserve water from aquifers.
We have to keep an eye on what we throw into the rivers or throw in the soils, because it can contaminate the water that we're going to need one day.

Words and processes of water that you should know

Recharge of an aquifer. It is one of the processes of the water cycle.
It consists of the natural or artificial water inlet of an aquifer.
"Recharge" is the right word to say that the aquifer receives water.

Hydrogeological map. It's the water map of an area.
This map shows, among other things:

• The size and thickness of the aquifer.
• Water levels.
• Water quality data.
• The recharge and delivery areas. 
• The water flow lines.

Text: Gemma Millán Malo
Translation: Lilia de Jesús Villalba Almendra
Validation 1: CAED 147, Cuautla, Morelos
Validation 2: APAMA, Spain