A septic system's lifespan should be anywhere from 15 to 40 years. How long the system lasts depends on a number of factors, including construction material, soil acidity, water table, maintenance practices, and several others. Concrete septic tanks have the longest lifespan out of any septic tank material. Pipes in your drain field system are usually made of PVC plastic, steel, or cast iron, which typically lasts up to 50 years if installed and maintained properly.