Everything You Need to Know About the Sewer Line

Everything You Need to Know About the Sewer Line

By Dikran Seferian January 17, 2022

A sewer line is an essential part of a house’s plumbing system. Although it is hidden away underground, out of sight shouldn’t mean out of mind. Many homeowners forget about their sewer pipes until an issue arises, and others aren’t even aware of their existence. Getting familiar with your home’s main sewage line and its design can give you an idea of what goes on in the concealed spaces. A better understanding of the sewage system's maintenance needs will also allow you to take preventative measures that keep your drain line running and in good condition.

What Is a Sewer Line?

Your home’s sewer line consists of a single pipe that carries the wastewater from the inside of your house to the sewer main that runs beneath the street. The pipe goes through the front lawn and is buried underground. The depth essentially depends on the climate area you live in.

In warmer areas, sewer lines can be as shallow as 18 to 30 inches deep. Colder climates, however, would require them to be at least 5 feet deep to prevent freezing. Typically, there would be a frost line under which the pipe is supposed to be installed.

Types of Sewer Lines

Choosing the Best Material for Your Main Drain Pipe

Choosing the Best Material for Your Main Drain Pipe

Depending on when your house was built and whether the sewer line has previously been replaced, there are several materials the pipework can be composed of. This is a key factor that may determine the possibility of future issues.


Clay pipes were widely used in older houses. Although they’re no longer common, clay pipes can still be used nowadays for new installations. The material can’t be degraded from exposure to chemicals. However, it tends to be heavy, difficult to cut and can break due to pressure caused by underground roots.


Orangeburg pipes are composed of wood fibers and waterproof adhesive. The material used to be a common choice among plumbers due to being light and easy to cut. However, Orangeburg isn’t the most durable option — it barely lasts 50 years and therefore is not recommended anymore.

Cast Iron

Cast-iron pipes are absolute champions in durability and you can still find them in many homes. Although not as common as modern plastic pipes, cast-iron is a possible option for new installations. On the downside, the material is rather heavy, expensive, and cutting it requires special equipment — but this shouldn’t be something to worry about if you already have cast-iron sewer pipes.


Two types of plastic can be used for underground sewage piping: PVC and ABS. Regardless of their similarity, they have different codes and make use of different adhesives. Moreover, PVC is normally white whereas ABS is black. The two types also have different attributes; PVC is typically known for its flexibility while ABS is relatively stronger. Both materials, however, are viable options as they’re easy on the wallet and are unaffected by the roots of trees.

Sewer Line Cleanouts

Advantages of Having a Sewer Line Cleanout

Advantages of Having a Sewer Line Cleanout

A common feature among home sewage lines is a cleanout. A sewer cleanout is basically a small part of a sewer line that you can access by unscrewing its cap. Should there be a clog in the sewer line, this feature makes it significantly easier — and less expensive — to open up the blockage.

To find out if your property’s sewer line features a cleanout, you simply have to look for it. Depending on the layout of the house, the sewer cleanout can be located anywhere. If it’s installed outside the house, you may find it concealed among the shrubbery. The first place you should consider looking, however, is around the vicinity of the bathroom.

If you have a basement, check the concrete slabs along the foundation walls. You shouldn’t have a hard time locating the sewer cleanout once you know where to search for it.

Sewer line cleanouts are must-have features of a home sewage system — especially if the issue of clogs is something you often deal with. If your sewer line doesn’t already include a cleanout, consider having one installed. Besides being cheaper and easier to snake than the mainline, a sewer cleanout allows water to be released in the case of a backed-up sewer line. This essentially prevents flooding inside the house.

When to Replace Your Sewer Line

The question of when to have your main sewer line replaced comes down to how it’s performing. If you notice that the line is backing up more than once each year, it may be worth digging up the affected area and repairing it — or replacing it altogether. In most cases, however, snaking the mainline every other year should be enough. Bear in mind that there is a significant price difference between having the line snaked and having it repaired or replaced.

Fixing a Clogged Sewer Line

Although you can normally use a drain snake to find and clear out a clog in the drain line, clogged sewer lines pose a bigger problem. This case requires a sewer drain snake driven through the sewage line’s cleanout. If your mainline doesn’t feature a cleanout, unclogging the pipe can be rather difficult, therefore warranting a professional plumber.

While you should generally clean your sewer line once every two years, certain cases may require you to take care of the situation on the spot. These cases may include warning signs such as:

  • Gurgling noises from the pipework
  • Bad odors emitting from the sewer
  • Constantly clogged drains
  • Water puddles around the basement’s floor drain
  • Backed up sewage in the toilet, bathtub, or drain
  • Water backing up in the shower or bathtub when the washing machine is in use
  • Water drains too slowly

How to Prevent a Sewer Line Clog

Tips on Preventing a Sewer Pipe Blockage

Tips on Preventing a Sewer Pipe Blockage

Sewer lines can be clogged due to several reasons. While certain causes are unavoidable, you can still prevent frequent blockages by taking a number of measures. Sewer clogs caused by tree roots and collapsed pipes, for instance, can’t normally be prevented. The measures you can take to avoid a clog, however, mainly involve monitoring what goes down the drain.

Solid items flushed down the toilet can get lodged somewhere along with the sewage. Washing down food debris in the kitchen sink may also contribute to a clogged sewer line. There are certain items in particular that you should avoid dumping in a drain.

Food Items That Clog a Sewer Line

Food waste tends to be heavier than regular sewage waste, which makes it harder to flow through the plumbing line as easily. Consider scraping your plate in a garbage container instead of washing it all down in the kitchen drain line. Food items that don’t belong in a drain include:

  • High-fiber scraps such as celery stalks, potato peels, and corn husks
  • Fats, oils, and grease (these tend to harden over time, eventually leading to a clog)
  • Eggshells
  • Coffee grounds
  • Starchy foods such as pasta and rice 

Non-Food Items That Clog a Sewer Line

What Not to Dump in Your Toilet

What Not to Dump in Your Toilet

It’s important not to treat your toilet like a trash can. Many items that homeowners tend to throw in the toilet don’t break down enough to pass through the sewer line. Eventually, they gather among each other and cause a blockage. Objects you should avoid flushing down your toilet include dental floss, cotton swabs, twist ties, rubber bands, and hair. Even items that are labeled “flushable” may eventually clog a drain line. These include wet wipes, paper towels, sanitary pads, tampons, and thick toilet paper.

Other Measures to Consider

Besides monitoring what ends up in the sewer pipe, there are other measures that may help reduce the risk of a drain line blockage. One simple step involves using one-ply toilet paper instead of two-ply — that is if you have the habit of throwing it in the toilet instead of the trash. One-ply toilet paper dissolves much quicker than its two-ply counterpart. Another measure you can take is to flush your plumbing system every now and then. This involves filling bathtubs, sinks, and washing machines with cold water to full capacity and draining them all at once.

Who Is Responsible for Your Sewer Line?

Home sewer lines are typically connected to the city’s sewage system that runs underneath the street in front of the house. Regardless of the connection, that doesn’t necessarily mean the city is responsible for repairing or replacing your sewer pipe. Therefore, it is a good idea to have a plumber’s number saved on hand should a clog occur. There are instances, however, where the blockage takes place at the junction of the mainline. In that case, the responsibility falls on the city.


Written by
Dikran Seferian

Written by Dikran Seferian