Experimental measurements were conducted for two apartments area with their own on-site sewage treatment plants in order to quantify the unit loading factors of various pollutants. The influent sewage discharged from the apartment areas was sampled three days a week at two sites and during four seasons. The daily experimental measurements for flowrates were carried out every 30 minutes. The analysis of the pollutant loadings such as BOD_5, COD_(Cr) and SS were made every two hours. The components of TKN and TP in the influent sewage were also analyzed in the preparation for the further improvement of current sewage treatment systems which may be applied as diagonostic tests for conversion toward advanced treatment systems. The result of the study were as follows ; (1) The average unit sewage flowrate 178. 1L/capita/day, (2) The average unit loadings for BOD_5, COD_(Cr), SS, TKN and TP were computed to be 32.4, 58.5, 19.9, 6.3 and 0.9g/capita/day, respectively.