What Is a Sewer Line and How Does It Work?
Most homeowners don’t think much about their sewer line until something goes wrong. It’s one of those systems that runs quietly in the background — until it doesn’t. Understanding what a sewer line is, how it works, and what can go wrong helps you catch problems early and make better decisions when something does come up.
Here’s a straightforward guide for North Metro homeowners.
What Is a Sewer Line?
Your sewer line is the main pipe that carries all the wastewater from your home out to the municipal sewer system or a private septic system. Every drain in your house — every sink, toilet, shower, bathtub, floor drain, and appliance — connects to this one main line.
It runs underground from your home, typically through your front or side yard, and connects to the city main at the street. In most North Metro homes the sewer line is anywhere from 4 to 6 inches in diameter and runs anywhere from 20 to 100 feet depending on how far your home sits from the street.
What Is It Made Of?
The material your sewer line is made of depends largely on when your home was built.
Clay pipe Homes built before the 1970s often have clay sewer lines. Clay was the standard material for decades and many of these lines are still in service today. The downside is that clay pipe uses bell and spigot joints that tree roots find very easy to penetrate over time.
Cast iron Common in homes built from the 1950s through the 1970s. Cast iron is durable but corrodes over time, and older cast iron lines can develop cracks, scale buildup on the interior walls, and joint failures.
PVC The standard material for homes built from the 1980s onward. PVC is smooth, resistant to root intrusion, and much more durable long term. If your home was built in the last 40 years, there’s a good chance your main sewer line is PVC.
Orangeburg pipe A fiber and pitch material used from the 1940s through the 1960s as a cheaper alternative to clay. Orangeburg deteriorates over time and is prone to collapsing. If your home was built during this era and has never had the sewer line addressed, it is worth knowing what you have.
How Does It Work?
Your sewer line works entirely by gravity. Wastewater flows downhill from your home through the main line and out to the street. The line is installed at a slight downward pitch — typically about a quarter inch of drop per foot of pipe — so that waste moves through without assistance.
Every fixture in your home connects to a branch line, which connects to the main sewer line. When you flush a toilet, run a sink, or drain a bathtub, the wastewater travels through the branch line, into the main line, and out to the street.
Your home also has a cleanout — usually a capped pipe located in the basement, crawl space, or near the foundation outside — that gives technicians access to the main sewer line for cleaning and inspection.
What Can Go Wrong?
Several things can disrupt the flow of your sewer line over time.
Root intrusion Tree roots are drawn to the moisture inside sewer lines and will work their way in through any joint or crack they can find. Once inside, roots grow and expand, catching debris and eventually causing a full blockage. This is one of the most common sewer line problems in the North Metro, particularly in neighborhoods with mature trees.
Buildup and grease accumulation Over time, grease, soap residue, and organic material build up on the interior walls of the pipe, narrowing the flow and eventually causing blockages. Kitchen drains are especially prone to this.
Pipe deterioration Older clay, cast iron, and Orangeburg pipes deteriorate over time. Cracks, joint failures, and corrosion can restrict flow and allow groundwater to enter the line.
Bellying When a section of pipe loses its downward pitch and sags, it creates a low spot where waste collects instead of flowing through. This is called a belly and it can cause recurring backups even after the line has been cleaned.
How Do You Know If Your Sewer Line Has a Problem?
The most common signs that something is going on with your main sewer line include:
- Multiple drains in your home are slow at the same time
- You hear gurgling sounds from drains or toilets after using water elsewhere in the house
- There is a sewage smell coming from a drain or your yard
- Your basement floor drain is backing up
- You have had recurring clogs that keep coming back after being cleared
Any one of these is worth a call. More than one at the same time usually means the problem is in the main line rather than a single branch.
How Is a Sewer Line Cleaned?
The two most common methods for clearing a sewer line are drain snaking and hydro jetting.
Drain snaking uses a flexible cable with a cutting head to break through blockages and pull out debris. It is effective for most standard clogs and root intrusion.
Hydro jetting uses high-pressure water to scour the interior walls of the pipe clean. It is more thorough than snaking and is particularly effective for grease buildup and heavy root intrusion. The result is a pipe that is as close to clean as it can get without replacement.
At Viking, we determine the right method based on what’s actually going on in the line — not what generates the biggest ticket.
How Often Should a Sewer Line Be Cleaned?
For most North Metro homes, having the main sewer line cleaned every one to two years is a reasonable baseline. Homes with mature trees nearby, older original pipe material, or a history of recurring backups may benefit from more frequent service.
The best approach is to not wait until you have a backup to think about it. A line that is cleaned on a regular schedule is far less likely to cause an emergency.
Serving the North Metro Since 1987
Viking Sewer and Drain has been cleaning and diagnosing sewer lines across Rogers, Maple Grove, Plymouth, Blaine, Brooklyn Park, Coon Rapids, Elk River, Osseo, and the surrounding North Metro communities since 1987. If you have questions about your sewer line or want to get it checked out, give us a call or book online.