摘要：Baron and Ngobaran Underground Rivers are two sources of water on the southern coast of Gunungkidul Regency, Indonesia. A state-owned water utility company (PDAM) is currently distributing raw water for drinking from these underground rivers to Tanjungsari, Saptosari, Paliyan, Panggang, and Purwosari. In addition to quantity, processing raw water for this purpose needs to consider water quality. Therefore, this study was designed to assess the quality of raw water along the PDAM service lines, starting from a common source through pipelines and, finally, to connected customer property lines, and to analyze its Water Quality Index (WQI). During the field survey, the water quality was measured directly at several points selected by the purposive sampling method and indirectly in the laboratory. These measurements observed physical (temperature and TDS), chemical (pH, NO 3 - , Cl - , CaCO 3 , Fe total, Pb), and biological properties (total coliform) and compared them with the requirements for drinking water quality published in the Regulation of the Minister of Health No. 492/MENKES/PER/IV/2010. The results showed that except for total coliform, all water quality parameters of Baron and Ngobaran Underground Rivers met the standards. Also, the detected water quality from the sources to customers’ taps formed a spatial variation. Based on the WQI analysis results, excessively high total coliform levels on all samples made the raw water biologically unsuitable for direct consumption. Therefore, boiling before use is highly suggested as it can remove coliform bacteria in the water.
