You need a leach field with a septic system or raw sewage can spill out and pollute your land and water. However, you can choose the type of septic system that best works on your property if a traditional leach field won’t do, such as if your water table is too high. In this case, you’ll need an alternative approved by your local municipality. One of the most common options is a mound septic system, where you place a leach field into a large mound of sand above the ground instead of having both the tank and leach field underground.