The report describes the assessment of the sludge formation and separation technology at the WTP Tlumačov in two measuring cycles (summer 2020 and spring 2021) in profiles: i) aeration, ii) effluent from the reaction tank, iii) flocculation, iv) sediment inflow, v) after sedimentation, vi) inflow to filtration, vii) after filtration, on the right and left line of ÚV Tlumačov. The report assessed the quality of raw and treated water and the effectiveness of destabilization and aggregation. The preparation of the suspension in the phase of fast and slow mixing and separation of flakes were evaluated. Aggregation tests (sedimentometric analysis) were used for this purpose.