Acta Scientifica Malaysia (ASM)

Langat River is one of the main sources of water supply for Selangor state. This study was conducted to determine the water quality status of Langat River in Selangor based on WQI and INWQS. Water sampling was conducted at ten stations for two seasons; dry season during February 2016 and wet season during November 2016. Parameters included in this study are temperature, pH, DO (Dissolved Oxygen), Conductivity, TSS (Total Suspended Soil), TDS (Total Dissolved Oxygen), BOD (Biochemical Oxygen demand) and Heavy metals. The laboratory analysis was carried out according to the HACH and APHA methods. This study found that the water quality of Langat River is classified in class III for both sampling times. Reduction in WQI value in the river was observed mainly due to human activities such as industrial and services building producing wastes. Based on results and statistical analysis, the values of pH, COD, Conductivity, TSS and TDS in the study area were influenced by the nearby industrial constructions. In dry seasons, low volume and stagnant water could create entropic conditions in the river. Water quality which classified in class III were considered as slightly polluted. Langat River can be used as supply if only conventional treatment was done. Water quality which classified in class III were considered as slightly polluted. Langat River can be used as water supply if only conventional treatment is carried out.