Gravity Septic Repair and Save the Old Drainfield
A well-designed and expertly built drainfield can last for thirty years or more before it needs replacing. When drainfields are built, an equal sized area (replacement area) is provided nearby to build an equal sized replacement drainfield in case the drainfield fails. Drainfields fail, usually because of sewage overload or sometimes just from old age. A failed drainfield usually has sewage on the ground, and the drainfield cannot be repaired in the short term.
However, if the drainfield is removed from service for a year, it usually can recover, because everything causing the failure is organic. Time alone can usually restore a failed drainfield. If it is possible to build the replacement drainfield in the provided area, and if you can leave the old drainfield intact and without a hydraulic connection to the new drainfield, you may be able to keep the old drainfield in service as an alternative or an alternating system. Once the old drainfield has recovered, you can switch them back and forth, usually on a yearly basis on an anniversary date.
If you can set up an alternating system, as per our examples, there is no technical limit to the potential life of the drainfields.