A greywater treatment arrangement for on-site household greywater effluent treatment, the arrangement comprising: - a septic tank, comprising a first inlet to receive the greywater from the household, an inner space to separate a substantial part of solids from the liquid greywater effluent by sedimentation for clarifying the greywater effluent to be treated, and a first outlet to discharge the clarified greywater effluent, and - a filtering apparatus comprising a container having a second inner space, a peat material bed disposed in the second inner space to form a filter medium through which the greywater effluent can flow by gravity, a second inlet at the upper part of the container to receive the greywater effluent to be filtered from the first outlet of the septic tank, a distribution device which is arranged at the upper part of the container to receive the greywater effluent from the second inlet, said distribution device being arranged to distribute the greywater effluent substantially evenly on the area of the upper surface of the peat material bed, and a second outlet at the lower part of the container below the peat material bed for discharging of the filtered and purified greywater effluent flown through the peat material bed, wherein the distribution device comprises a distribution tray arrangement which is arranged inside the container above the peat material bed, said distribution tray arrangement comprising a plurality of chutes, each chute having a bottom (30, 31) and one or more holes (32, 33) arranged on the bottom (30, 31), characterized in that the bottom of each chute comprises a lower bottom part having first holes, and a higher bottom part having second holes located at an elevated level in relation to the level of the first holes, so that in the event of a low effluent flow the effluent may be distributed on the peat material bed only through the first holes, and in the event of a high effluent flow the effluent may be distributed on the peat material bed through the first holes and the second holes, and in the event of clogging of the first holes the effluent may be distributed on the peat material bed through the second holes. - a septic tank, comprising a first inlet to receive the greywater from the household, an inner space to separate a substantial part of solids from the liquid greywater effluent by sedimentation for clarifying the greywater effluent to be treated, and a first outlet to discharge the clarified greywater effluent, and - a filtering apparatus comprising a container having a second inner space, a peat material bed disposed in the second inner space to form a filter medium through which the greywater effluent can flow by gravity, a second inlet at the upper part of the container to receive the greywater effluent to be filtered from the first outlet of the septic tank, a distribution device which is arranged at the upper part of the container to receive the greywater effluent from the second inlet, said distribution device being arranged to distribute the greywater effluent substantially evenly on the area of the upper surface of the peat material bed, and a second outlet at the lower part of the container below the peat material bed for discharging of the filtered and purified greywater effluent flown through the peat material bed, wherein the distribution device comprises a distribution tray arrangement which is arranged inside the container above the peat material bed, said distribution tray arrangement comprising a plurality of chutes, each chute having a bottom (30, 31) and one or more holes (32, 33) arranged on the bottom (30, 31), characterized in that the bottom of each chute comprises a lower bottom part having first holes, and a higher bottom part having second holes located at an elevated level in relation to the level of the first holes, so that in the event of a low effluent flow the effluent may be distributed on the peat material bed only through the first holes, and in the event of a high effluent flow the effluent may be distributed on the peat material bed through the first holes and the second holes, and in the event of clogging of the first holes the effluent may be distributed on the peat material bed through the second holes.