When a property for either a home or commercial building is evaluated for a septic tank installation, the inspector is checking to see if the site is suitable for onsite waste water treatment. An evaluation is very important because it helps protect homeowners from incurring costs in the future if there is a problem due to the location of the septic tank, and it protects the public and environment by ensuring the waste water will be disposed of and returned to the water table in a clean and healthy manner. Below is a general guide on how a septic tank site evaluation is performed: