Coal mine pit lakes (voids) can provide an alternative raw-water source in areas with limited access to conventional water supplies, but their use requires continuous assessment of water quality and appropriate treatment. This study evaluated the water quality of a more than 12-year-old former coal-mining void in Loa Ipuh Darat, Kutai Kartanegara, East Kalimantan, Indonesia, and assessed its potential and sustainability as a raw-water source. Water samples were collected from four sampling points and analyzed for physical, chemical, and microbiological parameters. Water quality status was evaluated using the Pollution Index (PI) and the National Sanitation Foundation Water Quality Index (NSF-WQI). Community perceptions were assessed using structured questionnaires and descriptive quantitative analysis. The PI value was 1.00, indicating that the water met the applicable quality standard and was classified as good. The NSF-WQI score was 87.34, also placing the water in the good category. Most measured parameters were within the Class I water-quality criteria, although microbiological indicators, total solids, BOD, turbidity, and several parameters approaching their respective limits require continued monitoring. Community acceptance was positive: 65.31% of respondents rated the treated water as good and 32.65% as very good, while the overall Likert-scale perception index was 86.12%. The findings indicate that the Loa Ipuh Darat pit lake has potential as an alternative raw-water source, provided that water treatment, routine quality monitoring, source-area protection, and community participation are maintained.