If you’re building a new home, schedule the excavation at a time when it’ll have minimal impact on the construction process. Typically, this is before paving the driveways and sidewalks, but after the main frame of the home is built. After passing a percolation test and receiving a building permit, your septic tank is ready to be properly installed. The price of your new septic system is based on the size of your home and the type of septic system selected.