What Is A Septic Tank? | Causes Of Failure | Advantages | Disadvantages

A septic tank is a chamber built of concrete, fiberglass, or polythene and is placed beneath the ground or underground.

 The Septic tank is the place where our domestic wastes accumulate for basic treatment.

Where is the septic tank needed the most?

If we seek to find a septic tank in city areas, then we won’t find it. This is because a septic tank is the alternative way of household water waste management. A municipal sewer system is the primary way of water waste management.

And in city areas, there is already a centralized sewer system. So, we never find it in city areas.

Hence, a septic tank is needed in rural areas where there are not any centralized sewer systems.

Septic tanks are also called onsite sewage facilities.

 How does a septic tank work?

 The word “septic” refers to the meaning of “infected with bacteria”. So, bacteria play a major role in the performance and efficiency of the septic tank. Without the presence of bacteria, the septic tank wouldn’t be able to operate up to its efficiency.

          1.   All water from our house like: from the kitchen, bathroom, etc. travels from the main drainage pipe into a septic tank.

2 The waste accumulated in our septic tank gets separated into three different layers.

The bottom layer is composed of sludge. Sludge mainly consists of inorganic solids and byproducts of bacteria digestion.

The layer above the sludge consists of liquid wastewater, as heavier solids sink to the bottom and lighted floats on the surface. This is also the reason why the uppermost layer consists of scums. The scums contain lighter materials like fats, greases, oils, etc.

3.   Microbes or bacteria exist naturally in the septic tank, which then starts degrading the sludge by eating them up.

4.   The excess liquid wastewater (effluent) in the first compartment flows to the second compartment through the baffle.

Again, microbes in the second compartment start to eat the remaining part of the sludge.

5.   Then the excess water from the second compartment flows to the drain field.

This means the water from the compartment gets discharged through the pipe in the soil, where those water gets absorbed by the soil and those water is filtered and purified in a different layer of soil. Finally, those water gets accumulated beneath the ground and can be reused as well, like groundwater.

6.    The bacteria present in the septic tank constantly keeps eating up the sludge. This is the reason the presence of sludge is reduced with time.


Causes of failure of septic tank

1.    Heavy usage of water in the house for a short period causes the overflow of wastewater from the septic tank.

2.    Heavy usage of chemical fertilizers while cleaning bathrooms or dishes. Chemical fertilizers kill bacteria’s presence due to which there will be slow sludge breakdown inside the septic tank. This causes more amount of sludge collected inside the septic tank causing septic tank failure.


These problems or failures might lead to the contamination of groundwater that we use to drink. Septic tank failure causes backflow of water from the septic tank to our household drains as well.


Symptoms of septic tank failure

·     An awful order around the septic tank and drain field.

·      Backflow of wastewater into household drains.

·       The soil around the septic tank gets muddy and pooling of water in the ground surface above the septic tank.

·     The grass or plants on the surface right above the septic tank are uneven greenery.


How to avoid these problems and maintain a septic tank?

1.   The first solution would be emptying(desludging) our septic tank at regular intervals of time by professionals.

Desludging is the process of pumping out the accumulated sludge from our tank by using a vacuum truck.

2.  Heavy use of a chemical in household drains should be avoided.

3.    The liquid containing enzymes and bacteria should be poured into the septic tank through a household drainage pipe from time to time.

4  The amount of water entering the tank should be reduced, especially over a short period.


Advantages of having a septic tank are:

·       Economical: Septic tanks can save money in the long run. We don’t have to pay monthly sewage and water bills to the municipality, as we don’t use their sewer system. Also because we don't have to install new pipes and plumbing costs can also be avoided. We just have to pay for the initial cost and occasional maintenance.

·      Long-lasting: Concrete septic tank can last up to 40 years, while a steel septic tank can last for 15-20 years. It depends upon how we use and maintain it.

·      Environment friendly: Once in a while, centralized sewer lines can leak the raw sewage into the ground causing contamination in groundwater. Since the septic tank doesn't flow through the sewer system and pipes, there is less chance of leakage. Also, the septic tank uses a natural filtration system that could minimize pollution.

·       Low maintenance cost: septic tank saves a lot of maintenance cost because for septic tank we just have to perform a desludging process every 3 to 5 years. Which will ultimately save the plumbing maintenance bill.


Disadvantages of having a septic tank are:

·     Cost of desludging: Even though we have to perform desludging once every 3 to 5 years, the cost required to do it is expensive.

·        Breakage of drainage pipe: For numerous reasons like interference by a root of a tree, vehicle running over a pipe, etc. the drainage pipe that connects household drainage and septic tank breaks. This creates a massive problem in detecting where the pipe is broken. Also, we wouldn't be able to detect the breakage of pipe in the required time, causing to generate unpleasant smell around our house, and pooling of water around the septic tank as well.


·    Water restriction: Wasting or utilizing a lot of water for a short time causes an overflow of water from the septic tank. This overflow generates unpleasant smells around our house, pooling of water, etc. This overflow occurs because when we use excessive water for a short period, then the water inside the septic tank won't get enough time to pass through the drain field and get into the soil, causing overflow from the top of the septic tank.