What is the difference between a main line and a sewer line?

Author: Dr. Ulices Wilderman DDS  |  Last update: Friday, February 20, 2026

Main drains are located in the walls and floors of your home, while sewer line drains are located outside underground. Each drain pipe in your home is connected to a different household fixture on one end, including toilets, sinks and bathtubs, and the other end is connected to the main sewer line.

What is the difference between sewer and water main?

Why You Should Know the Difference. When you think of sewage and water lines, you can view them as two lanes of traffic. Sewage is outbound, taking dirty water away from homes and commercial properties. Water lines are the inbound lane, bringing clean water into homes and businesses.

What are the three types of sewer lines?

There are three main types of sewer systems: Sanitary sewers, stormwater sewers and combined sewers. Some households are attached to septic systems, but these systems do not attach to offsite sewer systems.

What is the sewerage main line?

The sewerage main line is the drainage pipe that is responsible for removing wastewater from your home. The sewerage main line will connect to the sewer system of the city such that wastewater of your home can be treated.

What is the difference between a drain line and a waste line?

Waste pipes are more directly connected to fixtures, handling smaller volumes of water, whereas drain pipes aggregate and transport this waste to sewage systems. Despite these differences, the terms are often used interchangeably, particularly in kitchen and bathroom settings.

A House Sewer Line Has 3 Types: Learn About Sewer Lines

Is the main line the same as sewer line?

Simply put, your mainline is your sewer line. And all your drains connect to your main line. Your main line is also the line that goes from your house to the city connection or your septic tank. Before leaving your home, all of your drains dump into your mainline.

What is the difference between a sewer drain and a main drain?

Main drains are located in the walls and floors of your home, while sewer line drains are located outside underground. Each drain pipe in your home is connected to a different household fixture on one end, including toilets, sinks and bathtubs, and the other end is connected to the main sewer line.

What does the main sewer line look like?

You may spot a 3 to 4-inch diameter pipe peeking out of the slab floor of the basement. The sewer drain pipe could be made of plastic or cast iron; it might be copper or brass in rare cases. The stub-out will have a screw-in plug coupled with a square-head lug on it, representing your access to the main drain.

Does each house have its own sewer line?

All the drains in your home lead to one main sewer line, which goes into the municipal system or to your septic tank system. Knowing the location of your sewer line is crucial, especially when issues arise involving clogs, backups or breaks.

How much to replace a main sewer line?

Sewer line replacement costs stem from labor, permits, materials, excavation, and landscaping restoration, potentially running from $4,000 to $25,000. Trenchless sewer replacement methods can save long-term costs by minimizing disruption and avoiding extensive excavation, despite higher initial charges.

What is the difference between sewer pipe and waste pipe?

Basically: Soil Pipes are designed to transport the soiled water (blackwater) from your toilet, urinal, or bidet (if you're fancy). Waste Pipes are designed to transport the wastewater (greywater) from your sinks, shower, bath, washing machine, or dishwasher.

How deep are sewer lines buried?

For instance, residential sewer line depth ranges from 18 to 30 inches. However, city sewer line depths are different. Your city's sewer lines must always be deeper than the deepest residential pipe to allow waste to flow downhill. As such, these lines can go as deep as needed.

What type of pipe is used for residential sewer lines?

PVC is unarguably the easiest sewer line pipe material to handle. The extremely smooth surface inside the pipe allows solids and liquids to pass without forming clogs. PVC pipes can work for most residential and commercial applications. They are more versatile because they come in diverse shapes and sizes.

Does the main sewer line always have water in it?

The second answer is NO: If you notice that drains are overflowing or making a gurgling noise or even sucking the water seal dry it would most likely point towards a fault in the drainage system.

Why is my sewer bill higher than my water bill?

The water released by the treatment facility is usually cleaner than the drinking water's receiving stream. Typically, the advanced systems are expensive to build and operate, increasing the overall cost of wastewater treatment. So, it is logical that sewer bills are higher than water bills.

What size is the main sewer line in a house?

Depending on your local plumbing codes, the main sewer line for residential homes is usually 4 inches in diameter. You may think if the pipe were larger, more waste could travel without getting clogged. But that's not true.

Can two houses share a sewer line?

Shared sewers can have implications on maintenance responsibilities and related expenses. Neighbors often share sewer lines, leading to potential disputes or joint resolutions.

What is the difference between a sewer line and a sewage line?

Can sewerage and sewage be used interchangeably? No! Sewerage and sewage are regularly used interchangeably, however, this is actually incorrect. Sewage refers to the waste that is discharged, whereas sewerage/sewers are the structure that the discharge goes into.

Does every house have a main water line?

Every house has at least one main water shut-off valve. Look for where the plumbing enters the home to find yours. There are a couple of main spots to check inside first before heading outside to look. You can save yourself some time by checking your property inspection report if you know where that is.

What is the pipe outside my house called?

One pipe is an air conditioning condensate drain, also commonly referred to as an AC drain line. These pipes are usually white in color and are made from PVC piping. Another pipe you may find on the outside of your home is a water pressure relief valve, also known as a PRV drain line.

How do I know if my main sewer line is clogged?

When the sewer line that carries waste away from the house is blocked, you'll notice the four signs that follow.
  1. All Your Drains Reek. ...
  2. Your Drains Are Blocked or Slow-Moving. ...
  3. You Hear Loud Gurgling Sounds Coming From Your Pipes Throughout Your Home. ...
  4. You Have an Unnaturally Lush Landscape or a Smelly, Sunken Lawn.

How long do main sewer lines last?

Generally speaking, you're going to find that most main sewer lines will only last somewhere between 50 and 100 years before you need to do a main sewer line replacement. You could very well have a broken sewer line on your hands right now and not even realize it.

How much does it cost to clean the main sewer line?

The national average rate for sewer cleaning prices ranges between $200 and $600, with most people paying around $250 for a main sewer line cleaning with minimal-to-no excavation to access the cleanout. This project's low cost is $150 for light-duty professional sewer cleaning with a snake.

What is the main sewer line in a house called?

What is a Main Line? To put it simply, your main line is your sewer line. It's a line located underground that carries all wastewater from your home to a municipal connection or septic tank, not just toilet water.

How to clear a main sewer line clog yourself?

Your step-by-step guide: How to clear a main sewer line clog
  1. Step 1: Loosen the cap on the drain pipe. ...
  2. Step 2: Open the cap and let the buildup drain out. ...
  3. Step 3: Feed the auger cable into the drain pipe. ...
  4. Step 4: Run the auger until the clog is clear—and beyond. ...
  5. Step 5: Hose down the pipe and auger cable.

Previous article
What helps sliding glass doors slide easier?
Next article
How to stain a lot of wood quickly?