The research was undertaken to study on the removal effect of turbidity and phosphates in drinking water system using polymerc aluminium coagulants. From the experimental results, 15~50㎛ size of muddy particles in raw water was effectively removed by polymeric aluminium coagulants (PACS), but small particle groups of 5~15 ㎛ was remained as 50% of orignal amounts in the treated water. Polymeric aluminium coagulants (Ca-PAX) were effective in reducing turbidity and ortho-phosphates (PO₄^3-), especially down to 1 ppm.