If you are building a new home with a septic system or replacing the septic system at an existing home, properly sizing the tank is important to ensure the septic system operates properly and provides many years of reliable service. The main components of a septic system are the drain line that collects the waste water from the residence, the septic tank, and the drain field (or leach field).
The drain line routes the waste water to the septic tank where it is held for about 48 hours to allow solid material to settle to the bottom and form the sludge layer and grease and oil to rise to the surface to form the scum layer. A series of baffles hold the sludge layer and scum layer in the tank while allowing the liquid effluent to flow into the drain field where it percolates into the soil.
Installing a septic tank that is too small will cause it to be overloaded with wastewater. The solid material will not have sufficient time to sink to the bottom or float to the top and will instead flow out into the leach field with the effluent where it will clog the drain field and ultimately cause the system to back up or for untreated sewage to make its way to the surface of your yard.
On the other hand, installing a septic tank that is oversized does not cause much of a problem. In fact, you may be able to go longer between scheduled septic tank pumping. Be careful not to get complacent – have the system inspected every couple years to see if it is time to have the septic tank pumped.
