What Is Wastewater?

Water and the Environment

If you’ve come to this article wondering, “What is wastewater?” then you’ve come to the right place. Here, you’ll learn what wastewater is, where it comes from, where it goes, how to examine it, and how it’s treated. When you’re finished reading, you’ll have the basics you’ll need to properly understand what wastewater is.

What Is Wastewater?

What Is Wastewater?

The World Health Organization (WHO), defines wastewater as water that contains enough contaminants to be unfit for drinking by humans. The ability to safely drink water is the measure used to judge water as waste. Not all wastewater is easily identifiable. The tiniest doses of some pollutants can contaminate large amounts of water. This is why it’s important to know where wastewater comes from.

Where Does Wastewater Come From?

There are two basic categories of wastewater sources caused by humans. The first source comes from people’s everyday consumption of products. The proper term for this kind of wastewater is “domestic” wastewater. Two of the largest sources of domestic contaminants are homes and cars. As people cook, clean, wash clothes, shower, and paint their homes, contaminants leak into the water. When people drive, they leave behind rubber, oil, gasoline, and other chemicals. All of these seep into water and make it unsafe to drink.

The second major source of wastewater is commerce. These sources are termed \”industrial\” sources of wastewater. Manufacturing and agriculture are some of the largest contributors to wastewater problems. Pesticides, pharmaceutical leftovers, and coolants are just a few examples of the chemicals businesses dump into water. Industrial waste is a problem because it contains high concentrations of contaminants that can pollute water very quickly.

Although difficult to categorize as domestic or industrial, runoff water is another source of contamination. When it rains, pollutants can be picked up as the rainwater runs across roofs, roads, or any other surface and collects in streams and storm drains.

Where Does Wastewater Go?

Ideally, wastewater goes to water treatment plants to be made clean again. If not, it runs off into natural sources of water such as lakes, streams, and rivers. Most local governments in the United States take responsibility for ensuring that water is clean and safe to drink. To do this, they take what is wastewater and separate out liquid and solid contaminants. Chlorine, special bacteria, and other chemicals are then used to remove most of the liquids that pollute water. Solid waste is often broken down and physically filtered out.


You now know what is wastewater: it’s any water judged unsafe for consumption by humans. You have also learned the major sources that contribute to the pollution of water. Finally, you now know how water is treated and made safe for drinking again.