Precast concrete septic tanks vs. plastic septic tanks

Septic tanks are the most common types of vessels designed for septic storage and treatment. A septic tank is one of the elements of a plumbing network that has a huge importance.

It doesn’t matter whether you want to install a new septic tank or replace an old septic tank with a new one, it’s important to pay attention to some factors. These are the capacity and material of the tank. When choosing a septic tank for your property, you need to pick the right material.

The material of septic tanks is important as it gives the durability and specific features of each type of septic tank. Depending on the material they are made of, septic tanks are divided into two types – concrete septic tanks (also called cement septic tanks) and plastic septic tanks (also called poly septic).

Each of these materials has its advantages and disadvantages. So by knowing them you can make the right choice of septic tank material that is suitable for your needs and saves you time and money.

Precast concrete septic tanks

Precast concrete septic tanks vs. plastic septic tanks

Concrete septic tanks can be of two types – precast (ready-made septic tanks that can be delivered to the place where you want to install them) and on-site ( septic tanks that  are built at the exact spot you want them to be). 

What are the advantages ? 

High strength level and durability

Concrete is a traditional type of material used for making septic tanks. One of the great benefits of this material is that it’s super strong and durable. It has more strength than plastic and it’s capable of enduring different factors such as intense vehicle traffic, heavy soil weight, soil shifting, backfill damage and the influence of the environment. 

Septic tanks made of concrete are extremely durable to the environmental conditions and changes in the soil. Another characteristic detail about them is that their strength increases over time. And for this reason they have a longer life-span than plastic septic tanks (up to 40 years), given that they are maintained the right way and regularly drained.

High effluent capacity

The weight of concrete is much higher than that of plastic, so concrete septic tanks are capable of handling a large amount of effluent. A high effluent level means less frequent pumping and cleaning.

Easy maintenance

Since concrete is a durable material, concrete septic tanks don’t require regular checks as often as plastic septic tanks do. 

Precast concrete septic tanks vs. plastic septic tanks

What are the disadvantages ?

High price

Installing a concrete septic tank is more expensive than installing a plastic septic tank аs the purchase price  of concrete septic tanks is high.

Difficult installation 

Since a concrete septic tank can weigh several tons and it’s massive, the transportation of  precast concrete septic tanks to a given property site won’t be an easy task. You need to use heavy-duty equipment for transporting the concrete septic tank, lifting it and setting it into a spot.

If you choose the option  of on-site pouring, you should know that it’s still more difficult compared to plastic septic tank installation.

Precast concrete septic tanks vs. plastic septic tanks

Complex repair

Concrete septic tanks are very durable to damage, but in the case of cracks their repair is more difficult compared to the repair of cracks in plastic septic tanks. 

Another fact about concrete septic tanks is that they aren’t much resistant to corrosion and high levels of soil acidity, especially when not maintained the right way.Therefore, if you know that the environment of your property’s area isn’t suitable for a concrete septic tank, the other option for you is plastic septic tank.

Plastic septic tanks

Precast concrete septic tanks vs. plastic septic tanks

Septic  tanks made of plastic are the modern version of concrete septic tanks. These types of septic tanks are premade and they can be installed right after delivery. They characterize with rigged outer walls and an elongated shape.

What are the advantages ? 


Plastic septic tanks are sold at a lower price than concrete septic tanks. And their lower cost is also because of the fact that their installation and transportation is also low-cost.

Precast concrete septic tanks vs. plastic septic tanks

Easy to install

Since plastic is a lightweight material, the weight of plastic septic tanks allows their transportation to be done with a regular truck. The installation of plastic septic tanks is also simple: you just need to dig a hole, position the plastic tank and connect it with the plumbing network. 

And  the completion of  these tasks doesn’t require a large number of people and much time and effort. 

Versatile and flexible

Plastic septic tanks can be installed in a variety of places. And their flexible structure makes them more resistant to cracks compared to concrete septic tanks. Another advantage of plastic septic tanks is that they are resistant to rust and water-based corrosion.

Precast concrete septic tanks vs. plastic septic tanks


Compared to concrete plastic tanks plastic septic tanks are more clean and resistant to bacterial growth.

What are the disadvantages ?

Low durability

Despite the fact that plastic septic tanks are built to be durable, they are still not as strong  as concrete septic tanks. Therefore their lower level of strength makes them vulnerable to  damage caused by heavy surface traffic, tree root systems, soil vibrations. 

Plastic septic tanks can be damaged just by the weight of heavy soil, when buried deep into the ground. 

Low effluent capacity

The role of a septic tank is to handle a large amount of sludge, scum and effluent. Since plastic septic tanks are lightweight and have a low-effluent level, they are not suitable for taking a big amount of effluent.

And because of their low effluent capacity, one of the common things that can happen with plastic septic tanks is the so called “floating”.This happens when the water level is highеr than normal and this  leads to an increased risk of damage to the plastic septic tank and the plumbing system. 

Precast concrete septic tanks vs. plastic septic tanks

Difficult to maintain

Because plastic septic tanks have low effluent capacity this requires their regular pumping and cleaning. In general, plastic septic tanks require more frequent maintenance than concrete septic tanks. Also, not every state approves the use of plastic septic tanks. So,you need to keep this factor in mind when you consider buying a plastic septic tank.  

In conclusion, your choice of a septic tank type will depend on factors like :

  • your budget
  • where is the location of your property
  • the environment 
  • the characteristics and quality of the area’s soil