The Tukad Badung River is polluted due to waste contamination from community activities. Community activities along the Tukad Badung basin produce considerable waste channeled into the river without processing. The Tukad Badung River water that flows downstream is collected to be used as a source of raw water for clean water at the Estuary Water Treatment Plant of PDAM Tirta Mangutama Badung Regency, therefore the water quality of the Tukad Badung River needs to be considered. Constructed Wetlands (CW) are wastewater treatment systems that can be used to reduce pollutants entering Tukad Badung. This study aims to measure the efficiency of a terracing CW system in reducing the pollutant parameters BOD, COD, TSS, and ammonia. A lab-scale hybrid CW reactor test applied a terracing concept. It is a combination of free water surface (FWS) and subsurface (SSF) CW and was made from a plastic container that was 83.5 × 58.7 × 45 cm and filled with media gravel and sand as a substrate. The reactor utilized water jasmine (Echinodorus palaefolius) and dwarf papyrus (Cyperus haspan), with the planned hydraulic retention time (HRT) for FWS and SSF being two days and three days, respectively. The study results show the removal efficiency values for the BOD, COD, TSS, and ammonia parameters to be 93%, 82%, 96%, and 39%, respectively. The resulting efficiency in ammonia parameters is less than optimal; this is caused by minimal adaptation time, resulting in plant roots not being ready to provide sufficient oxygen supply for the nitrification process.