Developments in agriculture, industry, and urban life have caused the deterioration of water resources, such as rivers and reservoirs in terms of their quality and quantity. This includes the Saguling Reservoir located in the Citarum Basin, Indonesia. A review of previous studies reveals that the water quality index ( WQI) is efficient for the identification of pollution sources, as well as for the understanding of temporal and spatial variations in reservoir water quality. The NSFWQI (The National Sanitation Foundation water quality index) is one of WQI calculation methods. The NSFWQI is commonly used as an indi-cator of surface water quality. It is based on nitrate, phosphate, turbidity, temperature, faecal coliform, pH, DO, TDS, and BOD. The average NSFWQI has been 48.42 during a dry year, 43.97 during a normal year, and 45.82 during a wet year. The WQI helped to classify water quality in the Saguling Reservoir as “bad”. This study reveals that the strongest and most significant correlation between the parameter concentration and the WQI is the turbidity concentration, for which the coeffi-cient correlation is 0.821 in a dry year, and faecal coli, for which the coefficient correlation is 0.729 in a dry year. Both parameters can be used to calculate the WQI. The research also included a nitrate concentration distribution analysis around the Saguling Reservoir using the Inverse Distance Weighted method.

This study explains water quality in terms of seven heavy metals in the Upstream Citarum River and analyses human health risk (non-carcinogenic risk) for adults and children. Water samples were collected from five sampling locations along the Upstream Citarum River, i.e. from Majalaya Sub-District to Dayeuhkolot Sub-District. The contents of heavy metals were analysed by the Atomic Absorption Spectrometer (AAS) variant 240 FS. The results of the analysis showed that the pollution index value, which was categorised as slightly polluted from the highest to the lowest value, was as follows: location 4 (4.220) > location 1 (3.764) > location 2 (3.219) > location 5 (2.967) > location 3 (2.800). Values of the hazard index ( HI) for adults and children were as follows: Pb > Cr > Cd > Zn > Ni > Co > Cu. Pb and Cr have HI values greater than 1. This indicates that these metals can have a negative impact on public health. The HI in the ingestion pathway was greater than that of the dermal pathway, and the HI value for children was greater than that for adults. Further research is needed regarding the health risks from groundwater around the area which is used directly by the community because river water and groundwater systems are interconnected through streambeds.