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Although there are three main types of septic system (Type 1, 2, and 3) used for residential operation, the majority of basic septic systems are a Type 1 system. There are two main components that make up a Type 1 septic system – a septic tank and a dispersal field/bed. All liquid effluent (both sewage and other wastewater) leaves the home through the plumbing system and is first piped into a septic tank through the inlet pipe.




Once in the tank, the effluent is partially broken down by the good bacteria in the tank. Some of the heavier solids will sink down and settle in the bottom of the tank – this is known as the sludge layer. Some of the lighter solids like grease and oils will float to the top of the tank – this is known as the scum layer. An experienced wastewater technician will be able to tell quite a bit about a system, including gauging how well and often it has been maintained by the depth of the scum and sludge layers in a tank. 



The remaining partially treated effluent will leave the tank through the outlet pipe and flow to the dispersal area. Ideally, there will be an effluent filter in the outflow baffle which will catch any sludge and sewage, preventing it from leaving the tank and blocking the dispersal area. In a typical gravity system, the effluent then travels down the outflow pipe to a distribution box. There, it is sent out evenly to the drain field pipes that coverage in the distribution box in order to ensure even distribution of effluence in the drain field. 



Some Type 1 septic systems cannot rely on gravity to get the effluent from the septic tank to the distribution box or may have a very high water table so may also require a pump chamber. The pump chamber is a second tank that also contains a pump and floats which sends the partially treated effluent to the drain field.






The dispersal field is where the partially treated effluent slowly percolates back into the ground. The drain pipes in a basic, gravity septic system are perforated with little holes where the effluent can seep out. The drain pipes are bedded in an aggregate (gravel and/or sand) which absorbs and further treats the effluent as it trickles through the holes. The aggregate and soil below filter any remaining harmful bacteria before the wastewater reaches the water table. The dispersal field, also known as the drain field or leach field, is where most of the issues with a septic system occur. Because it is buried and not visible to the home owner, issues with the drain field can happen without much warning and can be very costly to replace. The only way to truly know the condition of a septic drain field is through inspection with a CCTV scope camera in order to visually inspect and assess each drain pipe. To prevent issues and keep a drain field flowing and operating as it was intended, it is strongly recommended that the drain fields is cleaned with a hydro-flush and power-auger every 3-5 years, or each time the tank is pumped.

Drain Doctors would be very pleased to help when needed, with septic inspections with CCTV camera as well as septic tank pump outs and drain field cleaning. Please do not hesitate to call our friendly office at any time for free advice or assistance with your septic system.







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