Septic tanks: what is it, drainage, how it works, sizes, types

Although a septic tank is a vital component for many people, this term can be quite foreign and unusual for some.

There is little chance that someone who has lived all his life in an apartment or in a house that was connected to the city’s sewer system will know what a septic tank is and what its role is.

But this is not a problem, because in this article we will focus on this information and make sure that after you finish reading this, you will know everything you need to know about a septic tank.

What is a septic system?

To truly understand how this system works and what all its features are, we need to start with the beginning.

And that beginning refers to the fact that we must first understand what a septic tank is.

In principle, it is a sedimentary reservoir that is buried in the ground and uses biological decomposition and drainage processes to treat wastewater coming from a house.

The inhabitants of a house usually produce a large amount of wastewater by using various household appliances and utilities, such as:

All this water must be drained somewhere, and this is where the system comes into operation.

It uses the benefits of natural processes and state-of-the-art technologies to complete this role.

As for the design of the system, this is a fairly simple one.

It consists of a round or rectangular tank that does not allow water to drain from it, and the components from which it can be made are various, such as:

  • cement
  • plastic
  • fiberglass

An important role of the reservoir is to stop sludge and scum from traveling to the drainage area.

Therefore, the T-shaped drain pipe and tank compartment are specially designed to perform this function.

Although the system is a fairly advanced technology, it is just a simple onsite sewage facility and can only provide a basic treatment of sewage.

But for a home that is not connected to the main sewer system or simply has a poor drainage system, a septic tank is an optimal and easy way to dispose of sewage.

All the household water and excrement removed by a house eventually end up in this large reservoir.

The use of this system is prevalent in rural areas.

As for the installation, this is done at a considerable distance from the house to which they are connected.

This distance is usually 50 meters.

They consist of:

  • two compartments
  • a tank which is supplied with domestic water through an inlet pipe

In cities, it is not necessary to use a septic system, as all the resulting wastewater will be taken over by the main sewer system.

Its maintenance and domestic water treatment will be handled by a local company that specializes in performing these processes.

It is a technology that has many advantages, allowing the occupants of a house to use all household services without problems.

But all these benefits come with their responsibilities.

To function as optimally as possible, and for as long as possible, the reservoir needs to be maintained constantly and regularly.

We must also not forget the effect that the use of a septic system can have on the environment.

This responsibility also falls under the care of the homeowners.

If the drainage area is filled with too much water, it can lead to flooding.

As a result, wastewater can come to the surface or create a return effect in toilets and sinks, an effect that no one wants.

How does it work?

Now that we better understand what a septic system is, it’s time to find out how it works.

It will be supplied with domestic water from a house.

Once the wastewater enters the reservoir, a process of separating its components takes place.

Following this separation process, 3 components will be obtained:

  • materials that can float on the surface of the water (for example oils)
  • solid materials that cannot float
  • used water

It will have 2 pipes that are connected to it:

  • inlet pipe
  • outlet pipe

The main role of the inlet pipe is to accumulate domestic water from the house, resulting from various daily household processes, and to transport and store it inside the reservoir.

This water is stored inside the tank for a long time until the above separation process is completed.

Upon completion of this process, the resulting wastewater will be transported through the outlet pipe outside the tank.

The main role of the outlet pipe is to spread this water evenly in the ground and different watercourses.

After a longer period of storage inside the reservoir, the separation process will begin and 3 different layers will emerge from it:

  • the surface layer which is made up of oils and fats and which can often be called “scum”
  • the middle layer which is represented by the wastewater and the various particles found in it
  • the lower layer which is made up of particles that are too heavy to float and sinks to the bottom of the tank, forming a layer of mud

The bacteria contained inside the reservoir play a key role in its optimal functioning, as they are responsible for the degradation of solid particles.

As a result of the degradation process carried out by the bacteria, the remaining water can drain smoothly through the outlet pipe.

Following the drainage of water, a layer will remain on the bottom which represents the sum of the other two layers that have not been removed from inside the tank:

  • oily layer
  • solid layer

This content should be removed during regular septic reservoir care sessions.

After observing all these characteristics, it becomes obvious why it is just a basic form of sewerage.

Types of septic tanks

Now that we have started to have a list of basic knowledge about what the system is and how it works, it is time to deepen our study and see what types of septic tanks can be used.

Various types of materials can be used to make them.

Depending on the type of material used for manufacturing, the characteristics of the tank will vary, and its durability and strength will be drastically influenced by the components used.

Let’s take a look at the most commonly used types of reservoirs.


The use of cement for manufacturing will give the reservoir a very long service life of decades.

However, despite the long service life, if a crack arises in the material of this tank, scum can leak out of the reservoir and the groundwater can make its way inside.

concrete septic system


Although steel is considered a durable material, systems that are made of this material usually last only 25 years before the rusting process begins.

This is the main reason why these types are less often chosen by homeowners.

This process of corrosion can be a major risk as if it arises on the surface, it could lead to a drastic deterioration of the strength of the tank. At that point it could no longer easily support the weight of the soil above it.

As a result of this process, an animal or a human could fall inside the reservoir, in the worst case.

One way to save money, in this case, is to replace only the affected upper surface if the rest of the tank is intact.


This construction material is not prone to cracks or rust, which is an advantage over the other 2 types of materials presented so far.

The weight of the reservoir made of this type of material will be significantly lower than that of other tanks made of other types of materials.

This offers a significant advantage when it comes to installing the pool in the ground.

But this benefit is not without its disadvantages, unfortunately, because this low weight makes the pool more susceptible to unforeseen movements at the installation site when the surrounding soil becomes saturated with water.


These types of reservoirs have a variety of benefits, such as:

  • increased durability
  • lightweight
  • low prices

Similar to ones made of fiberglass, systems made of plastic do not rust and are not as susceptible to cracking as those made of cement.

Their lightweight makes them very easy to install.

But unfortunately, since they are so light, the risk of being damaged during the installation process is increased.

Also, if the installation process of these tanks is not done properly, the possibility of them starting to float to the surface is very high.


These types are what homeowners use when installing any other type on their land has failed.

The peculiarity of these tanks is that they are supplied with electricity.

The disadvantage of these special types of reservoirs is that their price can be 3 times higher than the price of another type.

But this increased price also comes with its advantages, such as the fact that they are much more efficient than other types of septic reservoirs and that they require a much smaller draining area compared to other septic systems.

This benefit can be taken into account by landowners of smaller terrains when deciding what type of reservoir to buy.

Although these types of installations require more frequent care sessions, their lifespan is long.


The unit used to measure the volume of a septic tank is galloons.

An optimal size must be able to keep the domestic water of a house for at least two consecutive days so that the process of separating solids and fats from the wastewater can be carried out.

To determine the required size of the reservoir, it is necessary to take into account the number of rooms in the house to which it is to be connected.

concrete sewer

Septic tanks considered standard have the following sizes:

  • 1,000 gallons
  • 1,250 gallons
  • 1,500 gallons

These sizes are usually sufficient for most homes.

Usually, for a home with between 1 and 3 rooms, a 1,000-gallon reservoir should be enough to meet the needs of the home.

A 4-bedroom home will need to be tied to a system of at least 1,250 gallons.

And a 5-room house will need a reservoir of at least 1,500 gallons.

installation of a concrete sewer

How often should it be pumped?

An ordinary septic system must be inspected at least every three years by an expert to ensure optimum functionality.

Some systems require more frequent inspections by experts, such as electric ones.

septic truck

Also, the reservoir should be pumped at least once every 3-5 years of use.

The frequency of pumping is influenced by a variety of factors, such as:

  • the size of the house to which the tank is attached
  • the amount of wastewater produced
  • the amount of solid material present in the domestic water
  • the size of the reservoir
sewage truck

Cesspool vs. septic tank

The septic tank is the main component of the modern septic system, which was invented 100 years ago and is one of the most widely used private sewerage methods.

The popularity of this sewage method is due to its minimal effect on the environment and ease of use, compared to other valid sewage methods.

Inside the reservoir are numerous deflectors that prevent heavy materials, such as sludge, from entering the outlet pipe.

installing a septic system

The garbage left inside is digested by various bacteria.

The drain pipe spreads wastewater evenly over a large enough area, while the sludge and scum remain in the reservoir.

On the other hand, the cesspool is a much older method of disposing of domestic water.

In principle, the cesspool is a block of cement with holes that are buried in the ground.

There is no uniform distribution of wastewater in this method.

All debris collects in this cement block, the sludge gradually accumulates, and wastewater and scum drain into the surrounding soil through holes.

The pit should be pumped frequently and relocated when the soil around it becomes saturated with water.

Nowadays, any cesspool system is often replaced by a modern septic system.


man strengthening septic system
How long does a septic tank last?

A septic reservoir today can last between 20 and 30 years.

The lifespan is influenced by many factors, such as:

the number of people living in the house to which the system is connected
the quality of the soil in which the reservoir is buried
the material from which it is made

How much does it cost to replace a septic tank?

The price of the reservoir replacement may vary depending on the following:

the size of the house to which it is attached
the degree of permeability of the soil in which it will be installed
the type of s
ystem purchased

On average, the price can range from $ 3,109 to $ 9,677.

How to tell if the septic tank is full?

There is a list of signs that if you notice in your septic reservoir, then it may be full:

formation of sewage puddles in the drainage area

a slow drain of water of the sink, toilet, or shower

an unpleasant odor around c
oming from the unit

gurgling sounds in the pipes of the house

What to do after the septic tank is pumped?

There is a list of activities that must be done after a specialized company has finished pumping your septic tank:

Organizing a regular pumping program with the company.

Pay close attention to objects that are thrown into the house’s sewer system to avoid filling the reservoir too quickly.

Understand the principle of the system and its components, to assist the specialized pumping company with any useful information on their next visit.

Time needed: 15 minutes.

How to find a septic tank?

  1. Use a septic tank map

    This is the first step that should be taken, as it is the easiest to do.

    Most cities have a map with all the septic tanks that have been installed in that area.

    This map should show you the exact location of it.

  2. Follow the pipes

    If you have not been able to find a map, the easiest way to find a septic tank is to follow the pipes coming out of your house.concrete rings on a septic system

  3. Look carefully at your yard

    Septic tanks are buried so that they are not easily visible.

    But that doesn’t mean it’s impossible to see them with the naked eye.

    Look for areas in your yard that are slightly higher or lower than the rest of the field.
    hole to find a septic system

  4. Ask your neighbors for advice

    Ask your neighbors if they know where their tank is located relative to their home.
    Most likely, yours will have the same digging up septic system

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