Purpose: Design of laboratory lamella settling tank used in the laboratory researches of sedimentation process, optionally in either cross-current or counter-current. Design/methodology/approach: This paper presents a selection of geometric parameters of the device made using numerical methods to analyze the flow in designed settling tank. Findings: As a result of analyses, of the final device design was developed that allows it to obtain the proper distribution of flow velocity. The simulations allowed the selection of the proper construction of the tank, in which the velocity distributions in successive channels are comparable to the fulfillment of lamella, which will allow it to charge uniform stream of liquid (suspension). Practical implications: The use of numerical methods of modeling the flow in the settling tank allowed to fine-tune the design of the device at the early stage, and in particular the parameters of the distribution of suspension. Originality/value: The settling tank allows sedimentation to take place in both configurations with the preservation of an identical sedimentation surface. This concept allows a comparison of processes in these systems at a given identical surface load.