Septic systems installed after the late 90's will typically have an effluent filter on the outlet end of the septic tank. The water passes through the effluent filter before it enters the drainfield. This filter helps to catch debris from entering the drainfield and potentially causing a blockage. If the effluent filter gets stopped up with debris you could experience signs of back up in your home. We recommend having the effluent filter cleaned annually to prevent back ups.