Septic systems can last anywhere from 15-40 years. There are a variety of factors that can lessen the life span of a septic tank such as the materials, if it has been damaged from vehicles driving over, groundwater flooding, natural disasters, or has experienced clogging. Wood septic tanks have the lowest life span while Concrete and HDPE septic tanks tend to have the longest life span. The best way to preserve the life of your septic tank is to have it regularly maintained every 6 and 12 months and getting it pumped every 3-5 years.