During the last years, multi-story buildings (MSBs) have been introduced in Arba Minch and other Ethiopian cities as condominium houses. Constructed at the edge of the city boundaries, they have a standardized design including flush toilets. The water supply scheme in place can hardly cope with the water demand inside the new buildings. Shortage of water causes many problems in bathing, washing and flushing toilets. These unhygienic conditions are inducing toilet blockage, smells in the houses, infection which can lead to a negative effect on health. The more people are moving into these condominium houses, the more these problems arise. The objective of this paper is to study the feasibility of rainwater harvesting (RWH) as additional water supply for MSBs. Two MSBs were selected as a pilot plot in Bekele Mola site. In this case, flashing toilet by rainwater could save 33 m(3)/month of potable water. That means we can reduce the use of potable water for non-potable-water needs by 42 L/household/d. This RWH system is recovering only 19.5% of water demand and 84% of flushing water demand with maximum 130 habitants at the pilot buildings. The supply is limited by the amount of rainfall and the size of the catchment area. In addition, the installation price is relatively high.