Concrete tanks are the most common type of septic tank. The cost to install a concrete septic tank is in the average price range. Concrete tanks are susceptible to cracking or separation, but usually are durable for a couple of decades.
Septic tanks made of fiberglass and plastic are less vulnerable to the rusting and cracking of other materials. Lower weight makes a fiberglass tank more susceptible to structural damage, however, and the tanks themselves can shift in soil.
Plastic is a durable, lightweight, relatively inexpensive material. Plastic septic tanks are less susceptible to cracking than concrete, and are incapable of rusting. However, because they are so lightweight, plastic septic tanks can be vulnerable to damage during installation. Also, if not installed properly, under certain conditions a plastic septic tank can float to the surface of the lawn. A plastic septic tank can be a less expensive installation option.
Steel septic tanks are the least durable and least popular types of tanks. Steel septic tanks have covers that corrode, which creates a risk that an unsuspecting person who steps on the cover might fall through it. Covers of steel septic tanks can be replaced separately if they should corrode.