This study aimed to enhance distribution uniformity of water flow through drip irrigation system network. The required Laboratory experiments for hydraulic tests and measurements were conducted at National Irrigation Lab of Agricultural Engineering Research Institute ((AENRI), ARC, MOLAR, Egypt. The distribution uniformity is affected by both pressure distribution along pipes and hydraulic characteristics of the drippers. The selected drippers were tested under operating pressures of (50, 75 , 100, 125 and 150 kPa), and the dripper irrigation lateral lengths were (35 ,50 ,75 and 100m). Two designs of drip irrigation were applied; first was closed circuits with two manifolds as a modification of traditional design, and the other design was the traditional with one manifold as a control. Three types of built in drip lines with flow rate of (4l/h) and two types of on line dripper with flow rate of (2 and 4 l/h) were calibrated. The results indicated that the closed circuits was the best specially when using lateral lengths (75 and 100m), but the values were nearly close in case of using lateral lengths of (35 and 50m). Maximizing distribution uniformity is possible for traditional design when using selfcompensating flow rate where it can reach value of 88.2% with 100m lateral length, the accepted lateral length in case of using built in drip line with 30cm spacing was 75m for closed circuits design where the DU % was 94% comparing with 79.2% for traditional design. The closed circuits had a significant positive effect in reducing friction head losses of non-pressure compensating built in drip line ranging from 20 to 41.7 % , where the percentage ranged from 10% to 50% for built in drip line with 50cm spacing – pressure compensating.