What is sewer water? The smelly truth

After you go to the toilet and flush, the water has to go somewhere. All the wastewater from your home goes into the main sewage drain. This drain is connected with a complex series of other drains that eventually lead to a treatment facility. There they treat the sewer water

Sewer water is the water that flows through a sewage system. In most cities, the sewer system primarily handles wastewater from kitchen and bathroom sinks, showers, and toilets. But some cities also have combined sewer systems that treat wastewater from both stormwater and wastewater sources.

Either way, wastewater from a sewer system is a source of pollution for rivers and groundwater if it is not properly treated. Sewer water contains lots of greases, oils, and soap scum. In other words, it’s not fit to drink, bathe in, or use for irrigation. If you live in a rural area, you might not have access to the city sewer and need to install a septic system to process your sewage.

Example of a water treatment facility. Image by PlumbingInstantFix. All rights reserved.

This article covers everything you need to know about sewer water.


What is sewage or sewer water?

Raw sewage is sewage that’s been untreated and hasn’t been sent through a treatment plant. It typically contains lots of dirt and chemicals.

Raw sewage can contain bacteria that can cause a lot of issues.  For this reason, it is important that it gets filtered and treated in a plant.

Treated sewage is the sewage that’s been cleaned and then sent back into rivers and lakes. 

Treated sewage, on the other hand, is harmless because it has been cleaned and then disinfected. Disinfection breaks down the chemicals so that they’re no longer harmful.

A sewage treatment plant uses a variety of technologies to accomplish this. Different regions have different preferences when it comes to the kind of treatment they want.

Why is raw sewage discharged into rivers and lakes?

To understand why raw sewage is discharged into rivers and lakes, you first need to understand how sewage treatment works.

Many cities use an inflow system where sewage drains into large pipes that carry it to wastewater treatment plants. These plants use primary and secondary treatment methods to remove most chemicals and bacteria from sewage.

But some smaller cities and towns still discharge raw sewage into rivers and lakes because they don’t have enough treatment equipment to handle the volume.

Discharging raw sewage into a body of water like a river or lake is illegal in most areas because it pollutes both the water and the soil. The soil can’t absorb all the toxins in the water because it has no way to get rid of them. The toxins also get into the food chain because the water is a natural source of nutrition for aquatic life.

Another reason is that the treatment facility can get overwhelmed when it rains a lot. This is why more and more sewage systems are splitting rainwater and sewage water so that it is easier to process it. A lot of people need to install a rainwater tank in their garden to deal with this water themselves.

How can sewage be treated?

There are many different treatment methods. The most common ones are “activated sludge” and “open-air” systems.

Activated sludge systems use bacteria to break down pollutants in wastewater. The bacteria is “activated” by adding chemicals like phosphate and sulfate.

Openair systems use oxygen from the air to break down pollutants in wastewater. This is why open-air systems also need a way to scrub the pollutants from the air so they don’t end up in our lakes and rivers.

A combination of treatment methods works best for each city. Different areas have different soil types, water sources, and ecosystems that need to be taken into consideration.

It’s important to use the right treatment method for the right situation. For example, if a river has little sediment in it, you wouldn’t want to use a treatment method that would remove the sediment.

Where does the toilet waste go?

There are a few different places treated sewage can go. The most common is into local rivers, which are then able to flow into lakes and oceans.

Some cities also send sewage into the ocean or a large body of water like a reservoir or the ocean.

This is done to protect the water supply during drought conditions. Here, the water is purified before being released back into the environment.

Once the water is in rivers and oceans, it evaporates into clouds. This water rains down on earth and from there it goes back into the ground. There are several layers in the ground that filter the water. Once this is done, cities pump it back up and filter it. From there we can use it again in our homes. As you can see, the water that we use forms a closed loop.

If we don’t clean or filter our sewage, we will get dirty water and problems. Therefore it is essential that we gather sewage water and clean it. This is a costly and long process but it is essential to get clean water. This allows us to use our plumbing systems and take a shower. 

To conclude, sewage is wastewater that comes out of our plumbing system. If you take a shower or go to the toilet, there is dirty water that leaves your house. This water has to be cleaned and filtered before it can be released into nature.

It is only fairly recently that we have started to create the complex drain system under cities. Treatment facilities have evolved a lot over the past few decades as well. We can expect to see better systems in the future as we develop better methods to treat sewage water. It is a smelly business but something that needs to happen if we want to get access to clean water. 

What is the difference between sewer water and wastewater?

Wastewater is broader than sewer water. It also includes water from sinks and showers.

Sewer water is only water from the toilet. It is only fairly recently that we have started to make this distinction.

It requires an upgrade of the plumbing drains as sewer water is collected separately from the other types of wastewater. This makes it easier to process it later on.

Most countries just let all the wastewater flow in the sewer and don’t make any distinction. It requires big investments in infrastructure while a lot of countries don’t even collect wastewater or waste (for example, in Peru it is often not possible to flush toilet paper).

We can expect that we will see more and more plumbing systems will have to separate the sewer water and wastewater. This will be a process that takes several decades though.

Rainwater also goes to the sewage processing system. It is being separated more and more though as heavy rainstorms could overwhelm these stations. More and more concrete is being used in cities and this results in more rainwater in the drainage system. French drains are often used to send rainwater from a garden to the drainage system.