The water of Lake Rawa Pening is used as a source of drinking water. Indonesian Government Regulation Number 82 of 2001 on Management of Water Quality and Water Pollution Control stated that the water quality of Lake Rawa Pening should meet the quality standard of first grade and be categorized as no polluted water. The purpose of this research was to assess the water quality based on Indonesian regulation and to assess water quality based on international regulations. The quality of water was assessed using a survey method in 7 sites of the Lake Rawa Pening 3 times for 3 months. Parameters measured were all the water quality parameters required in accordance with Government Regulation No. 82 of 2001. The results indicated that there were 13 values that exceeded the water quality standard of first grade. These exceeded parameters were total suspended solids (TSS), biological oxygen demand (BOD), chemical oxygen demand (COD), orthophosphate (PO4), NO3, As, Se, Cd, Mn, Cu, Pb, H2S, faecal coliform, and total coliform. Water quality status of Lake Rawa Pening was categorized as heavily polluted. The water quality of Lake Rawa Pening should be improved by reducing the pollutants entering the lake by restriction of human activities causing lake pollution.