2 minutes reading time (479 words)

Surface Vs. Groundwater


There are two types of water from which we gain our water supply: surface water and groundwater. Just looking at their names, it’s hard to tell the difference between the two. So what is the difference between these two sources of water?

Let’s start with surface water. Surface water is any water supply that’s on the surface of the earth. If you can see it, it’s surface water. Lakes, oceans, seas, rivers, reservoirs: all are considered to be surface water. Surface water serves multiple purposes in our daily use. It provides drinking water and public-use water, is used in irrigation systems, and is used in thermoelectric power. Of all the water used in the United States, over 70% is surface water.

Usable surface water is actually pretty scarce. Oceans make up over 95% of the surface water supply, but salt water can’t be used for crops or consumption. We rely on freshwater, which only accounts for 3% of the total surface water on Earth. This is why pollution and increased temperatures from climate change are a cause for serious concern: if our limited supply of freshwater is tainted, evaporates, or is otherwise rendered unusable, we’ll be in serious trouble. It can take hundreds, even thousands, of years for a surface water supply to be restored.

While our surface water supply is precious and limited, there’s a great amount of water beneath the surface of the Earth. This is groundwater.

When it precipitates, some of the water evaporates and returns to the atmosphere, some is absorbed by the flora, some stays in surface water, and some sinks into the ground. The water that’s absorbed by the ground doesn’t just disappear; it’s drawn by gravity deeper and deeper into the Earth, until it reaches the bedrock of the earth’s crust.

The bedrock is made of multiple types of rock. Some rocks are dense, like granite or clay, which prevents the water from being pulled all the way to the earth’s core. Other rocks, such as limestone, are porous, and allow the water to seep into the cracks and crevices. Over time, the porous rocks are worn down, forming voids of space where water can accumulate. These aquifers are where groundwater is stored.

Groundwater is a critical resource for rural communities in particular. 99% of the rural population in the US relies on groundwater for drinking water. How do we get to the groundwater? With wells! Wells reach the groundwater and pull water from the aquifers and water table.

Functioning wells are necessary in order for most rural populations to have access to safe, clean drinking water. That’s why we’re dedicated to providing rural communities of the southeast United States with financial and technical assistance in building and maintaining well systems.

If you are facing water, wastewater, or housing issues, please reach out! Let’s work together to see how we can help.

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Monday, 17 June 2019

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