Abstract: Numerous public sanitary engineering construction projects has been delayed and failed to complete on time, time management is found as the main reason for the unsuccessful completion of projects. This research is conducted to mitigate the delays faced by public sanitary engineering construction projects that occur due to time management. Time buffers are introduced and explored widely in this research with means of resolving the encountered delays. To achieve this goal, the following three objectives are set; identify and evaluate the delays that urge the need of engaging time buffers in sanitary construction project, analyze the location of time buffers, and develop models to size time buffers required to reduce delays. A questionnaire survey is conducted that covers the whole population of 100, and 84 responses received resulting in 84% response rate. After thorough analysis of the responses by using Relative Importance Index (RII) it is discovered that the main sources of the delays that scored high and more than 0.8 are during the prerequisite phase of the projects, namely: prerequisite work, project characteristics, and site or environment condition. Moreover, case study consisting of 10 public sanitary construction projects from Ministry of Works (MoW) is conducted that contributed directly along with the questionnaire, and with the support of former methods and models in developing the best mathematical models to solve the delays. Two mathematical models are proposed in this research that are effective and sufficient in eliminating or mitigating as much as possible the delays that affects the completion of the projects. The models have been interpreted and tested on previously executed projects of the case study to examine their validity. Accordingly, 90% and 80% of the tested projects show better results using the proposed model I and proposed model II, respectively.