A study on the health impact of improved rural water supply with piping system was done in 2 (two) sub districts Tanjungsari and Rancakalong, Regency of Sumedang, West-Java. Two desas in each sub district have been selected for the study. In each, 2 (two) kampungs supplied with piped water system were used as study areas, while the other 2 (two) similar kampungs without piped water system were used as control areas. The study result shows that the prevalence rates of conjunctivitis, skin and diarrheal diseases were significantly lower in the study areas than those in the control areas. The conclusion was that there was a positive health impact of the improved rural water supply in the study areas, especially in reducing the above mentioned diseases. In developing the rural water supply and in the communicable disease control program, the indoor watersupply piping system is highly recommended.