The Kumatsugi district of Sekinomiya Town, Hyogo Prefecture, is a depopulated ski area which is located on the East of Chugoku Mountains. The purpose of this paper is to clarify the developing process of domestic water supply and drainage systems in the Kumatsugi district, and to make clear the factors which affected the process.<br>In the second half of the 1950s, the residents of each settlement in the Kumatsugi district constructed their own small-scale water supply facilities. The purpose was to improve their standard of living.<br>From the first half of the 1960s to the first half of the 1970s, ski tourism developed in the Kumatsugi district and tourist accommodation increased in many settlements. The residents reinforced their water supply as the need for accommodation increased. The settlements which had no proper water source were given water supply facilities by the Sekinomiya municipal government or were eventually included in one of the facilities of other districts.<br>From the second half of the 1970s to the second half of the 1980s, the flush toilet replaced the older Japanese toilets in the developed settlements. Sewage was treated by means of a household purification tank (johkasou) for night soil. The sources of water supply in these settlements were reinforced for the increasing use of flush toilets. However, water pollution in the Kumatsugi district became more serious because untreated wastewater was being discharged and the treatment ability of the household purification tank (johkasou) for night soil was unsatisfactory.<br>Since the first half of the 1990s, many businesses have gone bankrupt. In the settlement in which the ski business is declining, residents accepted a proposal to construct a municipal water supply and sewage facility. In the most developed settlement, a small-scale sewage system was constructed by the municipal government as water pollution became serious. There is no municipal water supply now. The settlements, where most of the tourist accommodation businesses closed down, had to depend on the municipal water supply and sewage facilities were constructed.<br>In short, due to the development of ski tourism in many settlements of the Kumatsugi district, the water supply and drainage systems in those settlements are superior to the others. That is, the development of ski tourism contributed to the progress of those systems. However, this interrupted the introduction of municipal water supplies and sewerage facilities in all settlements. Consequently, the water was more polluted in the Kumatsugi district than in other districts.