Great septic info from the US Environmental Protection Agency!
2 reasons to routinely take care of your septic system (from the US Environmental Protection Agency):
A key reason to maintain your septic system is to save money! Failing septic systems are expensive to repair or replace, and poor maintenance is often the culprit. Having your septic system inspected regularly is a bargain when you consider the cost of replacing the entire system.
Your system will need pumping depending on how many people live in the house and the size of the system. An unusable septic system or one in disrepair will lower your property value and could pose a legal liability.
Protecting health and the environment:
Other good reasons for safe treatment of sewage include preventing the spread of infection and disease and protecting water resources. Typical pollutants in household wastewater are nitrogen, phosphorus, and disease causing bacteria and viruses. If a septic system is working properly, it will effectively remove most of these pollutants.
To read the full publication, click on the link!