When thinking about water underground, the water table is a good place to start. As water seeps into the earth it eventually reaches a point where the rocks and soil are full of water. The water table is the top “surface” of this underground, water-saturated area.
Think about digging a hole on the beach. After a few feet, water seeps into your hole and fills it up. The top surface of the water would be the water table. You can look down the beach and see this surface is about in line with the ocean!
The water table is not just a straight line underground. It varies based on the land or geology of the area. The water table level can change throughout the year based on precipitation (or lack thereof) and/or land activities such as agricultural irrigation. For example, during the summer the water table level can fall due to lack of rain and plants taking up water.
Underneath the water table, spaces which are full of rock, sand, soil, or sediment and allow water to be stored (and flow) are called aquifers. We pull ‘groundwater’ out of these aquifers for our drinking water. It is important to be aware of how much water we are pulling out of the aquifers and how much is being replenished. In some countries around the world, the water table has dropped permanently to the point where replenishment from precipitation is not possible.
Taking measurements of the water table can be useful and sometimes easy. Many environmental companies monitor water levels by digging wells and measuring down to the foot where water appears. Using these measures across an area can be helpful to understand where the water table is and how it is being impacted over time.
No matter where you live, conserving water and keeping out pollution is important – both now and for our future generations!
Go in depth on water tables with National Geographic: https://education.nationalgeographic.org/resource/water-tables-and-aquifers
