AERATION UNIT. This 3375ltr aeration treatment unit was custom fabricated for a local West Auckland septic tank installer. Wai Water septic tank services specialises in keeping Aucklands septic tanks working. This unit was fabricated to replace an old failed sand filter on a local property in West Auckland. 3375 litres of aeration, with venturi sludge return, 2 x 500mm manholes, pumpout chamber, sealed electrics box. Fabricated from 12mm HMWPE, tri-extrusion welded and pressure tested.