Abstract: An irrigation system is disclosed. The system features a pair of lines placed generally parallel and proximate to each other in the subsurface. Only one of the lines is directly connected to the water source. The other line serves as an auxiliary to permit the system to be flexibly adapted or expanded to meet changing irrigation demands or landscape conditions. The auxiliary line is separated into discrete segments, each segment pertaining to a selected zone or area to be separately irrigated. Feeder lines run from each discrete segment to sprinklers. Water is provided to the segments via valved bridges extending from the main line to the segment, so that water flows to the segments only by way of the bridges, the bridges permitting separate segments to be activated in a planned manner.