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When properly designed, installed and maintained, septic systems can have a minimum life expectancy of 20 to 30 years.
The Basic Design
A septic system usually consists of 3 main components:
- Septic tank
- Distribution Box
- Soil Absorption System (SAS) – a system of trenches, galleries, beds, chambers or pits which receives effluent from the septic tank or distribution box and transmits it to the soil.
Wastewater drains from the house, via a sewer pipe to the septic tank. There, it is kept for a day or more to allow the solids in the wastewater to separate from the liquids. The layers of scum and sludge remain in the septic tank where bacteria found naturally in the wastewater work to break down the solids. Gases are released through a plumbing vent located on the roof of the house.
After the wastewater is allowed to settle and separate in the septic tank, the partially treated liquid flows out of the tank and into the distribution box where it is uniformly distributed into the Soil Absorption System (SAS) below the surface of the ground.
The SAS treats the wastewater by allowing it to slowly trickle from perforated pipes or chambers into a layer of stone and then down through sand and soil. The stone and soil in an SAS act as biological filters to remove toxins, bacteria, viruses and other pollutants from the wastewater. It is this filtering process, along with the biological action, that cleanses the liquid so that it is made potable by the time it reaches the aquifer and drinking water supply.
Title 5 Inspections
Title 5 of the Massachusetts State Environmental Code requires that all septic systems be inspected by a certified inspector at the time of transfer of property, change of use, or expansion.