Septic tanks do not require additives to work correctly, but with proper treatment, including regular pumping and protecting the drain field, a septic tank should last for many years. Most homeowners should have their tanks pumped at least once every three to five years, but increasing the number of people living in the home decreases the time the homeowner should wait to pump it again.
Protect the tank and drain field by keeping vehicular traffic off of them. Tank materials may include concrete, vinyl or fiberglass. While they can withstand foot traffic in the area, the weight of a vehicle can cause the top of the tank to collapse, damaging the automobile and the tank. Vehicles also collapse the soil of the drain field and increase the chances of failure.
Limit the use of detergents and household cleaners to amounts recommended on the label directions. Do laundry throughout the week instead of all at once so the tank has time to recover after each load. Doing multiple loads of laundry in a single day forces the helpful bacteria out of the tank and increases the load on the drain field. When the loads are spread through the week, the bacteria have time to reproduce between them, and the drain field has time to recover.