A septic system is a small onsite sewage treatment and disposal system buried in the ground in which w aste matter is decomposed through bacterial action.
Household waste flows out of the house via a connecting pipe to the primary chamber of the tank. Organic solid material floats to the surface and forms a layer of what is commonly called "scum." Bacteria in the septic tank biologically convert this material to liquid. Inorganic or inert solid materials and the byproducts of bacterial digestion sink to the bottom of the tank and form a layer commonly known as "sludge." As the primary chamber of the septic tank fills up, this digested material or effluent flows through a connecting pipe to a secondary chamber. This is where the final settling and digestion process in the tank takes place. From the secondary chamber, the effluent passes through an outlet pipe into the leach field for the final purification process. Only clear water should exist between the scum and sludge layers. It is this clear water that should overflow into the soil absorption area.
Irst, the sludge that accumulates int he bottom of the tank must be pumped out periodically. There is no additive that you can put in the tank that will deal with the sludge. IT MUST BE PUMPED. If not pumped, the sludge will eventually overflow into the soil-absorption area. This will clog the system, and it will need to be replaced, at enormous expense and inconvenience.
Second, the bacteria necessary for the digestion of the solids needs to be maintained. If bacteria-killing products are used in the home, the bacteria should be replenished. If the bacteria level is too low, the solids may not be digested properly causing the solids to build up too much and overflow into the solid absorption area. Make sure to use only USDA approved bacteria replenishment products that are engineered specifically for septic tank maintenance.
Frequency of pumping depends on the capacity of the tank and the number of people in the house. If your house has a standard 1,250 gallon tank and you have 3-4 people, the tank must be pumped every 2 to 3 years. If you use a garbage disposal, it's like adding another person to the equation and accelerates the buildup of sludge.
Pumping involves vacuuming the wastewater sludge and scum out of the tank chambers with a large tank truck equipped with a high capacity vacuum pump system. The waste is then transported to a designated municipal wastewater treatment facility for processing. In some rural areas, septic tank contents can be applied directly to the land if treated properly.
With proper septic tank maintenance your system should last between 20 and 30 years.
You can read more information about the use of caustic soda flakes and surfactants here.