Constructed wetlands were used to improve water quality in a Malaysian lake. Water, sediment, and plant samples were analyzed to assess the effectiveness of the wetlands. The results showed that the water quality parameters in the lake met national standards, with significant differences across sampling sites. The wetlands also showed significant improvements in water quality, with strong correlations between certain parameters. Sediment samples revealed significant differences in heavy metal concentrations, with strong positive correlations between some metals. Plant samples also showed varying concentrations of heavy metals across their tissues.