what is a sewer lateral - sewer pipes and cables in trench

What is a Sewer Lateral? You Might be Surprised!

What is a sewer lateral? You might not have heard this word before, but you do know it.

It’s perhaps the most important run of pipe in your home or building. Why? Because it’s vital for running a safe, healthy home. In this post, we’re going to walk you through the basics of a sewer lateral.

So, What is a Sewer Lateral?

A sewer lateral is the run of pipe between your building and the city’s main drain sewer. All waste in your home eventually goes into the sewer lateral, which then carries it away to the public sewer system through the city’s main drain. The city’s main drain is usually in the street in front of your home.

But here’s the surprise. This sewer lateral is more commonly known as your home’s main drain, main line, sewer pipe, or main sewer line. There are probably even more variations. Whatever you call it, a plumber will know what you’re talking about if you ever need him or her to check it out.

A building’s sewer main collects sewage from all of the building’s branch lines and carries it into the public sewer. In other words, your sewer main is the only thing that transports sewage from your home, office, or other building to the city’s sewer.

what is a sewer lateral - illustration
The diagram above illustrates a sewer lateral on a homeowner’s property and how waste is carried from the home to the city’s main sewer system.

Sewer Lateral Facts

Here are some interesting facts about sewer laterals in general.

  • All new main lines are made of PVC, polyvinyl chloride, but many older lines are made from cast iron or clay piping.
  • Cast-iron pipes are notorious for rusting out underground and being very prone to clogging.
  • Clay pipes last much longer than cast iron, but are much more fragile and prone to roots. Over time, large gaps form between the different sections of clay (or terra cotta) pipes, because they are fitted together, not glued or threaded. Trees can grow on the side of a mountain, so if there are any gaps in the pipes, roots will find their way in. Because of this, PVC pipes have become the gold standard for sewer laterals.
  • PVC has been used since the 1970s and is not going anywhere soon. It never rusts, is sturdy, and is completely watertight. Tree roots can penetrate PVC pipes, but it is far less likely than with clay or cast iron.
  • Most homes have a 4-inch main (the diameter of the pipe). However, in some cases, homes use a 3- or 6-inch main.
  • The sewer lateral is buried 12 inches below the water line but could be deeper. The water line is different in every area. To get an accurate estimate of depth, contact a plumber (who has special camera equipment) or your city for documentation.
  • In most cases, your homeowner’s insurance will cover damage to your sewer lateral. Check with your insurance agent to make sure this is the case.
  • Sewer lateral repairs or replacements are extremely expensive. Which is why they should be cleared of debris and cleaned once every two years. A camera can be used to inspect the line and a Hydro-Jet is used to clean it thoroughly.
What is a sewer lateral - tree roots in sewer pipe
Tree roots are one of the most common problems for sewer laterals. If even the slightest crack or pinhole is in the pipe wall, roots will gravitate to the water and insert themselves into the lateral. Eventually, the lateral gets blocked, breaks, and must be excavated and repaired or replaced. Hydro-jetting a sewer lateral once every two years is recommended for proper cleaning and maintenance.

Who is Responsible for the Sewer Lateral?

A “right of way” is a property line for plumbing. The right of way is important because if there is an issue with a sewer lateral, the right of way is used to determine who is responsible to pay for the repairs.

  • Property Owner: responsible for maintaining the plumbing on their side of the right of way
  • City (Municipality): responsible for maintaining any plumbing on their side of the right of way
what is a sewer lateral - diagram of sewer line responsibility
The city’s right of way starts at the road or sidewalk, as you can see in this diagram. Most people assume that ownership stops or starts at the property line, but this is not the case for plumbing.

Final Thoughts

Were you surprised to learn that a sewer lateral is what you probably call a drainpipe or sewer line (or something else)? Most people are.

But now you know the proper name. More importantly, you know what makes it so vital to your home and worth maintaining regularly.

Call 1-Tom-Plumber

Don’t hesitate to contact us here or call us at 1-Tom-Plumber (1-866-758-6237) if you need help inspecting or repairing a sewer lateral.

1-Tom-Plumber’s certified team of plumbers and drain technicians respond immediately to any emergency plumbing, drain cleaning, or water damage problem. We also handle the excavation of underground water lines and sewer main lines. Our immediate-response team is available every day and night of the year, even on holidays.

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