What is a Sewer System? Types, Purpose & More

A sewer is a pipe or conduit used to transport waste that typically does not flow completely (Gravity Flow).

Since the flow is under pressure, the full-flowing sewers are known as force mains.

In this article you’ll learn:

Purpose of the sewer.
Types of sewers.
Lots more.

So, if you’re ready to go with sewers, this article is for you.

Let’s dive right in.

What is a Sewer?

Sewers that collect wastewater from homes and businesses typically function as open channels or gravity flow conduits.

Sewers typically run through the middle of busy streets.

Access is challenging, and renovations influence both the community’s quality of life and the region’s economy.

Purpose of Sewers:

In a few locations, pressure sewers are utilized, but they are expensive to maintain and practical when there are substantial water consumption limitations or when the terrain makes it impossible to operate gravity flow conduits effectively.
Water from sewage is extracted, treated, and recycled in sewer mining.
Recycled water from a sewage mining operation is frequently utilized for irrigation, toilet flushing, cooling, fire suppression, and irrigating sports fields, parks, and golf courses in residential areas.

Types of Sewers:

1. AC (Asbestos Cement) Sewer:

Sewers consisting of asbestos cement (AC) are composed of cement and asbestos fibre.

Domestic sanitary sewage can be transported through asbestos cement (AC) sewers.

The ideal asbestos cement sewage pipe for conveying sullage from higher levels of multistorey structures is vertical (in two pipe systems of plumbing).

Pros of an Asbestos Cement (AC) Sewer:

Smooth and lightweight
simply bored, fitted, and cut
resistant to soil corrosion

Cons of Asbestos Cement (AC) Sewer:

Heavy loads cannot be supported by brittle.
As they are handled and transported, they are readily shattered.

2. Brick Sewers:

Large sewers are built using brick sewers, which are manufactured on the spot.

For the building of combined sewers or storm sewers, brick sewers are highly helpful.

Concrete sewers are now used in place of brick sewers.

Brick sewers may develop deformities and develop leaks.

A lot of manual labour is required.

Note: The brick sewer should be coated to prevent leaks.

3. Cement Concrete:

PCC – up to 60 cm in diameter

Small storm drains should use this. Not lasting.

RCC for dia > 60 cm,

They can be precast or on-site cast and withstand high pressure, corrosion, and severe loads.

These weigh a tonne and are challenging to move.

4. Cast Iron (CI) Sewers:

These sewer systems have high strength and durability and are waterproof.

Sewers made of cast iron are capable of withstanding strong internal pressure and external stress.

The following situations call for the use of cast iron sewers.

When sewage is transported while under high pressure.
When the sewage line is subject to a large external stress, i.e. beneath a highway, a railroad line, a foundation wall, etc.
And when there is a significant temperature differential.

5. Steel Sewers:

Steel sewers are flexible, impervious, light, and resistant to high pressure.

Pressure is used to transport the sewage.
The sewage needs to be transported over a river while submerged.
The sewage must pass beneath a railroad track.
Typically, outfall and trunk sewers employ them.

6. Plastic Sewers:

PVC sewers are now used to transport sewage.

This sewer made with plastic resists rusting.

Such sewers are smooth, lightweight, and easily bendable.

Plastic sewers cannot be used in very hot locations due to their high thermal expansion coefficient, though.

7. Stoneware or Vitrified Clay Sewers:

Sewers made of stoneware or vitrified clay.

Stoneware or vitrified clay sewers are formed of pipes made of clays and shales with certain qualities.

The lengths of stoneware pipes are 600 mm, 750 mm, and 900 mm, due to cost factors, pipes with internal diameters higher than 380 mm are rarely employed.

Stoneware pipes come in 600 mm, 750 mm, and 900 mm.

These pipes have spigot and socket ends; thus, socket and spigot joints are used to connect them.