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Is a plastic septic tank better than concrete?

Which are better - concrete or plastic septic tanks?

Considering a septic system installation for your property? When it comes to septic systems, there are many factors you must consider. You might have considered factors such as the size of the tank and location, but did you know that the material your septic tank is made of is equally important? Plastic and concrete are popular septic tank materials. So which is better?

In this article, we will discuss the advantages and disadvantages of plastic and concrete septic tanks. Keep reading to learn more.

Plastic Septic Tanks


  • Resistant to corrosion and cracks.
  • Lightweight - easy to transport and move and does not require heavy machinery for installation or transporting the tank
  • The lids and the connections have a snug fit and do not allow the water to seep outside the tank
  • Cost-efficient
  • They have a long lifespan and do not get damaged by tree roots


  • The plastic tanks are lightweight and can get damaged during installation. They need to be handled carefully and special attention should be paid to avoid contact with any sharp objects.
  • If the installation is not done properly, the tank can float to the surface of the ground. The tanks can float in saturated soil if a ballast isn’t installed.
  • Plastic tanks can also get deformed in certain types of soils. They are sensitive to soil conditions and can break due to changes in temperature.
  • Plastic tanks can break due to the weight of the soil or if vehicles drive over the land where they are buried.
  • They need to be inspected regularly for effluent levels.
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Concrete Tanks


  • Concrete tanks are durable and can last for decades
  • Available in a range of sizes
  • There are low chances of the concrete tank getting damaged during the installation process.
  • They have a high level of effluents
  • Concrete tanks are heavy and do not get affected by the soil conditions or vehicles driving over the land. Unlike plastic tanks, they are stable and don’t float to the surface
  • Resistant to temperature and climate changes
  • Suited for large households as they can handle large amounts of sewage waste


  • Concrete tanks are often more expensive than plastic tanks.
  • They require heavy machinery like cranes or trucks for installation so the site needs to have access clear access.
  • It is expensive to maintain and repair concrete tanks.
  • Concrete tanks are prone to cracks and leaks in harsh weather conditions.
  • They can get corroded over time and lead to toxic waste leaking out. Which can not only contaminate the groundwater but also lead to a terrible mess and potentially cost a lot of money in repairs.

In addition to installing the right septic system, you will also need to schedule regular maintenance to avoid leaks as wastewater can quickly contaminate the groundwater and harm the surrounding environment.

Plastic or Concrete Tank: Which is right for you?

Both concrete and plastic tanks have their advantages and disadvantages. Plastic tanks can be cost-effective but can be fragile if not installed correctly, whereas concrete tanks can be more costly but offer durable, long-lasting waste treatment. Concrete tanks are suitable for large properties as they need a large space for installation. Our wastewater specialists can determine which tank is more suited for your specific property. Depending on the site, access for machinery such as a crane, and soil type. Our experts will assess whether a concrete or plastic septic tank will suit your site better.

Contact Express Wastewater for your Septic System Installation

If you are in South East Queensland our licensed wastewater specialists can guide you on the right septic tank for your needs. Call us at 1300 722 517 for a free 30-minute consultation. Alternatively, fill out our online booking form and our friendly staff will get in touch with you.