Filterless water filtration is a method used to separate particles from wastewater using Dean flow, a secondary flow perpendicular to the main flow, in curved channel. The positions of the particles in the channel depend on three forces, wall interaction force, shear gradient lift force, and secondary flow drag force. In this work, a one loop spiral channel of 34 cm diameter with 20x5 mm2 channel cross-section was constructed in acrylic slab to filter out large colloidal particles from wastewater. Computational fluid dynamics simulation was done to visualize secondary flow and locate equilibrium position with various flow rates inside curved channel. It was found that, with the flow rate between 8.3 and 11.3 ml/s, a couple hundred microns size particles were able to be filtered out. This device can be further developed and used to alleviate clean water crisis in rural area.