Understating Septic Tanks

The tank is a critical part of the septic system. The tank is physically large but is usually underground and out of the way, so many people don't bother about it. However, knowing more about the tank can help you care for your septic system. Below are some things you should know about the tank. 


The septic system needs somewhere to hold waste as it decomposes. The tank provides the decomposition place. The tank receives wastewater from the house, holds it as bacteria break down the waste, and separates it into liquid and solid constituents. Solid waste accumulates in the tank, and liquid waste exits the tank and flows into the drain field.


The main material requirement is that it should be able to survive underground without damage or deformation and be watertight to prevent waste from leaking out of the tank or water seepage into the tank. Below are common tank materials.


Fiberglass is reinforced plastic—the reinforcement makes the material stronger than conventional plastic. Fiberglass tanks are lightweight, watertight, corrosion-proof, and affordable.


Concrete tanks are heavy and are unlikely to float out of the ground like lighter materials. Concrete tanks are also durable but require significant monetary investments relative to tanks of other materials.


Metal tanks, mostly steel, are heavy and don't float out of the ground easily. However, metal is susceptible to corrosion, and corrosion weakens metals. Thus, metal tanks are not as popular today as they used to be.


Plastic tanks' low weights make them easy to transport and install. They are also resistant to corrosion and are relatively affordable. Due to the lightweight nature of plastic, contractors must anchor plastic tanks to prevent them from floating out of the ground during wet seasons.

Shape and Size

Septic tanks are typically round, rectangular, or oval. However, the tank's shape is not critical as long as the tank can stay underground, hold adequate waste, and not leak. Thus, the tank's size is more significant than its shape.

Below are factors determining septic tank sizing:

  • The number of people in the household—household size determines the waste volume
  • Your household water usage habits—more water means more waste
  • The number of bedrooms in the house—more bedrooms usually translate to more people, which means more waste
  • Government regulations—local codes determine minimum tank sizes for different households

Septic sizing is a science. Your septic contractor will do the calculations and advise you on a suitable tank size. Contact a local septic tank installation service to learn more.