As of 2015, the average septic tank installation is about $4,600. The cheapest installation is about $800, but the installation can cost as much as $12,000, depending on the size and materials.
Some of the material options include concrete, steel and fiberglass. Concrete tanks are the most common type of septic tank and it fall in the middle of the price spectrum, but they are susceptible to cracks. Steel septic tanks are the least popular type of tank because they are susceptible to rust. Fiberglass tanks are less vulnerable to cracking, but they can shift in the soil and might be susceptible to structural damage due to their lower weight.