This work seeks to examine how private sector participation in water sector improves services for the population particularly in rural area basing on the case study of Killiwater Company in Rombo District. It is an attempt to show the significant increase of private sector participation (PSP) in the water supply sector in recent years. However, the Private sector referred in this work is a non profit organization which operates under the financial control of the German development agency (GTZ) in Tanzania''s rural water sector.The property right theory and public choice theory has been used as the theoretical frame work of this work in building this case. The study intends to reveals the contemporary wrong advices concerning private sector failure. The results are useful for future policy area as the work concentrates mainly on good performance so as to provide alternative policy advice and best decision making approach.