In recent years, the poor population in Nigeria still increases; however, Lagos located in the southwest city of Nigeria has the largest water slum in the world - Makoko floating community. They depend on fishing and fish processing for their livelihoods. There are 150 thousand people living in Makoko slum. Although located on the Lagos lagoon, it lacks sewage system. The condition results in water shortage, respiratory disease and the death rate rising. Through the principle of solar water distillation, we develop the architectural form of Steam Gallery to collect condensed water, and providing free water to residents. Also, we use the method of steam treatment so that residents can ease breathing problems. The attached spaces are the public bath and a natural fish pond. The former is another use of distilled water to reduce the chance of direct contact with the sewage and also decrease the possibility of disease. The latter is combined with the space of boat parking to provide the temporary storage. It is used by local recycled woods as a structure, and built by easy way for residents. Finally, we copy it in other areas to help the poor improve their lives.