This study was carried out to investigate sewage treatment efficiencies using water hyacinth (Eichhornia crassipes) and watercress (Oenanthe Javanica). In the hyacinth system about 30% of COD introduced was removed during 2 days of hydraulic retention time, and about 30$sim$50% of COD was removed in the watercress system during 1.2$sim$2 days of hydraulic retention time. Therefore, COD loading of $76sim170$ kg $COD/ha{cdot}day$ was removed during 2$sim$3 days of hydraulic retention time at the 0.18 $m^2$ area in the water hyacinth-watercress continuous system. Also 40$sim$50% of N and P in the sewage were removed in the tested water hyacinth-watercress system Although COD, N and P concentrations in the final effluent were still higher than the limits of waste discharge, applicability of this waste water treatment system should be further investigated as an alternative method far small scale sewage treatments.