Recently, the PPP(Public-Private-Participate) program on water and wastewater services in Korea has been under an active debate. However, the controversy has reached the limits of getting more valuable implications from past foreign experience beyond conceptual and/or qualitative case studies. This paper analyze scientifically and quantitatively the Buenos Aires Water Concession Project focused on propriety of the contract using system dynamics modeling. The results show that Buenos Airess Project has several problems in the contract phase even though Argentina government spent much time to design it. Analysis results suggest that estimation of K factor considering delay effect and future uncertainty, reduction of the first fixed terms of contract, etc., are needed for a proper contract.