In Septic Knowledge Center

Whether you’re looking at installing a new septic tank or replacing an existing one you’ve likely seen plastic and concrete septic tank options. Most homeowners are not especially excited about the prospect of spending a large amount of money on something that simply manages wastewater. However, this investment is one that shouldn’t be made lightly. They each have pros and cons and we hope that this list helps make your decision a little clearer.

Plastic Septic Tanks

Plastic septic tanks are becoming a common alternative to concrete tanks. These are pre-made and are typically an oblong oval shape with ridges along the outside walls. They can be bought easily at most home improvement stores and are ready to be installed once they arrive at your house.


  • Lighter/Easy to Install

Because they are made of plastic, they are relatively lightweight. They usually weigh a couple hundred pounds and can be easily moved by a regular truck. This means that installation is not only easier, but all the costs associated with it are lower too. All that is required is digging the hole, placing the tank in position, and connecting it to the rest of your system.

  • Cheaper

Because plastic septic tanks are lighter and easier to install, they are a cheaper alternative to concrete septic tanks. This savings is usually greatest when looking at installation cost, but you may also save money on the tank itself.

plastic septic tank martin septiciCons

  • Weaker

Plastic septic tanks are weaker than their concrete counterparts. This means that driving anything over the tank may crush or damage it.  Plastic septic tanks are also more sensitive to environmental factors such as soil vibrations and root penetration which can crack or warp the tank. Sometimes this damage can be repaired but depending on how bad it is, the tank may need to be replaced.

  • Low Effluent Levels

Septic tanks require an appropriate balance of sludge (solids), effluent (water), and scum (lightweight solids) to operate properly. Plastic septic tanks are lighter and unable to handle as much effluent as a concrete tank. If too much builds up inside the tank it can overflow your system and cause the tank to “float” to the surface of the soil, damaging the surrounding plumbing lines.

  • Require More Maintenance

Because plastic septic tanks cannot handle high levels of effluent, they also require more maintenance than concrete septic tanks. You will have to get them cleaned more regularly to prevent buildup within the system. This is an important factor to consider when looking at the overall cost of each system.

Concrete Septic Tanks

Concrete septic tanks are a more traditional option. You can choose from having a pre-cast concrete septic tank delivered to your home or have a tank poured in place. The premade option is ready to be installed as soon as it arrives. The poured in place option involves digging the hole and creating a mold to form your tank.


  • Durable

Unlike plastic septic tanks, concrete septic tanks are very durable. These can usually be driven over without any damage. However, this is not true for your plumbing lines leading to or from the tank, so you still need to be careful where you drive.

  • High Effluent Levels/Less Maintenance

Because concrete septic tanks are heavy, they can handle high levels of effluent without any problems. This means that they require less frequent maintenance and cleaning than plastic.


  • Heavy/Expensive

One of the biggest cons to a concrete septic tank is how heavy they are. They can weigh several tons depending upon the size your home requires. This amount of weight obviously requires heavy machinery to move and install, resulting in a higher overall cost.

  • More Difficult to Repair

Concrete septic tanks are less likely to be damaged, especially by environmental factors such as soil vibrations or root penetration. However, if they do become damaged or cracked, they can be more difficult to repair than plastic tanks.

If you’re still not sure what the best choice is for your home, please contact us. There are many factors that go into determining the best system for you. We’re happy to discuss the various options, the pros and cons, and what they mean for you.

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