Good water drainage is one of the most important things to consider when designing highway. Inadequate drainage facilities can lead to premature deterioration of the pavement and the development of adverse safety conditions such as cracks and rut. It is common, therefore, for a sizable portion of highway construction budgets to be devoted to drainage facilities. In essence, the general function of a highway drainage system is to remove rain water from the road and the highway right-of-way. This paper presents a study of the vertical drainage properties and the deterioration trends in water seeping of the pavement by testing the laboratory pavement section models with 2% slope which is very important in the selection of a suitable pavement surface layer and the base of the pavement. It has been concluded that by increasing number of days, when the pavement being saturated, the more amount of the water will runoff and the time of ending runoff increased by 77.78% after 138 days of study. The rut depth appeared after 2816 of wheel repetitions and recorded a 83.87% of rut depth increase after 109 days of load repetitions under different rain intensities with three durations of time.