Main Line vs Drain Line Which Pipe Does What?

Main line refers to the primary or original source of water supply. The term comes from the idea that a main line runs through a city, town or village. When you turn on the tap, you get water from the main line.

Most homes in developed countries have a main line running through their property. This means they have access to safe drinking water. In developing countries, however, where there isn’t enough clean water, some communities rely on wells. These wells are often contaminated with bacteria, viruses and other pollutants.

When plumbing a home or commercial building, there are two types of pipes: Main line and drain line. The difference between them is important because they carry different fluids at different pressures. If you don’t know which pipe does what, you might get water damage from a leaky pipe.

Plumbing systems consist of three main components: (1) the supply lines, which bring water into the house; (2) the distribution system, which brings the water to where it goes through fixtures such as faucets and toilets; and (3) the drains, which take away waste water.

A common misconception is that the main line carries water to the fixture, while the drain line takes away the waste water. In reality, both the main line and drain line take away waste water. The main line carries water under pressure to the fixture, while drain line carries waste water out of the fixture.

Main Line vs Drain Line – Which Pipe Does What?

The main line has a higher flow rate than the drain line. It also carries water under greater pressure. Both these factors make the main line more efficient.

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Drain Line

Water flows through the drain line from the fixture to the sewer. The drain line usually has smaller diameter than the main line.


Fixtures are devices for using water. They include shower heads, kitchen sinks, bath tubs, washing machines, etc.

The Most Common Types of Sewer Line Pipe - Pratt Plumbing


Sewers collect all the waste water from your home. The sewage can be treated by a wastewater treatment plant.

Wastewater Treatment Plant

Wastewater Treatment Plants use various methods to remove impurities from the sewage. Some plants use biological processes, others use chemical processes , and still others use a combination of both.

What is a main line?

A main line is a large-diameter pipe that delivers water from the water company’s main station to your home. A main line typically consists of several smaller pipes called service lines. Your local plumber will install the main line.

What is a Drain Line?

A drain line is a pipe used to transport waste water from your sink, bathtub, toilet, etc., to the sewer. Most toilets have one drain line.

How do I tell if my main line needs repair?

If you see any signs of leaks around your home, call a professional plumber immediately. Leaks could lead to serious problems, including flooding and mold growth.

If you notice that your water bill seems high, this may mean that your main line needs repair. Call an experienced plumber immediately.

What Causes A Clogged Sewer Pipe?

Clogs occur when solid matter gets stuck inside the pipe. When this happens, the water cannot move freely. There are many reasons why clogs form. Here are some of the most common causes:

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Buildup of sediment

Over time, sediment builds up in the bottom of the pipe. This buildup blocks the pipe and prevents water from moving smoothly.

Tree roots

Roots growing near the sewer line cause the soil to compact over time. This makes the soil hard and dense. The roots then grow down into the pipe and block it.

Animal waste

Animals like raccoons, squirrels, birds, or other animals leave behind animal droppings. These droppings create a thick layer of material on top of the pipe. Over time, this build-up becomes so thick that it forms a plug.


Molds thrive in moist conditions. If there is too much moisture in the area where the pipe is located, molds can grow quickly and cause a clog.

Why Do House Drains Smell So Bad?

House drains smell bad because they are not properly maintained. Dirty house drains allow bacteria to multiply rapidly. Bacteria produce foul odors as they decompose organic materials.

What Is A Main Sewer Line Cleanout?

A clean out is a tool used to remove obstructions from a drainage system. It is also known as a “manhole cover.”

Identifying the Parts of a Home Drain System

The purpose of a clean out is to prevent tree roots from entering the drainage system. Roots can damage underground pipes and cause them to leak.

When should I have a main sewer line cleaned?

Have a main sewer line cleaned every five years. You can schedule a cleaning with a licensed plumber at least once a year.

What Are The Different Types Of Plumbing Systems?

There are three basic types of plumbing systems: gravity flow, pressure (piped), and vacuum.

Gravity Flow System

This type of system relies on gravity for draining water away from the building. Water flows through a series of pipes until it reaches the lowest point in the building. Gravity alone does not provide enough force to push the water through all parts of the building.

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Pressure Piped System

This type of system uses pressurized water to deliver water throughout the building. Water enters the building through a single pipe called a service line. From there, the water travels through a network of pipes until it reaches each fixture.

Vacuum System

In a vacuum system, air is pulled through the pipes by a pump. As the air passes through the pipes, it picks up dirt and debris. The cleaner the air, the less likely it is to carry contaminants.

How to Find the Main Sewer Line in Colder Climates?

If you live in an area with cold weather, you may need to find the main sewer line before digging. In colder climates, the ground freezes during the winter months. If you dig without first locating the main sewer line, your excavation could become blocked with ice.

How to Locate the Outside Sewer Line Cleanout in Warmer Regions?

If you live somewhere with warmer weather, you will want to locate the outside sewer line cleanout before starting work. Digging around the house can disturb wildlife living nearby.


Plumbers are highly trained professionals who know how to fix any problem that comes their way. They work diligently to ensure that all of their customers’ homes are safe and comfortable places to live.

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