National Sanitation Foundation Water Quality Index (NSF-WQI) is used to determine the level of water quality,
based on 9 parameters such as: BOD, DO, nitrate, total phosphate, temperature, turbidity, total solids, pH, and Fecal
Coliform. In this study, 8 parameters were applied without fecal coliform, hence there was a modification of weight
as shown at Table 3. The modification was allowed if the water quality number reduced. Modified total weight score
remained 1. Weight score modification of each parameter was proportional with its original weight score.
Furthermore, the weight score (Wi) was multiplied by the sub-index value (Li) of parameter-i curve (Figure 2),
obtained by Calculator NSF-WQI Online (http://www.water-research.net/watrqualindex/index.htm). Then it will be