Septic tank filters

A filter unit for use in cylindrical casing means adapted to be disposed in a septic tank including:

• a plurality of stacked disc-dam units to form a cartridge having a longitudinal axis where each disc-dam unit has a generally circular planar base with a chord segment cut away to form a chord edge where the chord edges of each disc-dam is in mutual alignment and first and second sealing edges are formed at the respective ends of the chord edge and the first and second sealing edges are parallel to the longitudinal axis and where each base includes a continuous elongate dam located on one side of the base and extending outwardly therefrom to terminate at a dam top where the elongate dam has a dam first end adjacent said first sealing edge and extends continuously to a dam second end at said second sealing edge to divide said base into an upstream and downstream side;
• retaining device to hold at least two disc-dam units in stacked relation with the dam top of one disc-dam unit facing one surface of the next base opposite the side carrying the dam longitudinal axis in spaced relation to engage said first and second sealing edges and outlet means whereby said outlet means communicating with said outlet of said casing wherein said casing is cylindrical having an open inlet at the bottom and a frustro conical deflector located over the inlet so liquid can enter the device by flowing through an annular area between the housing and the base of the deflector and solids carried by the liquid are emitted through the opening formed at the apex of the deflector.