Economic Viability of Water-Supply Gravity Main

A water supply gravity main does not require power input; thus, it is preferred in comparison to a water supply pumping main. Moreover, a gravity main has greater reliability because it does not have moving parts, e.g., pumps and motors, and is independent of power requirement. Availability of a regular power supply at a required current and voltage is a problem in many parts of the globe. For a gently sloping topography, the gravity main involves large pipe diameters. Thus, in comparison with a pumping main, a gravity main may be uneconomical due to large size and associated overall cost. A review of the literature indicated that there is no guideline available for the adoption of a gravity main for a gently sloping terrain. In this investigation, a criterion has been obtained to ascertain if a gravity main or pumping main will be economic for a given gentle terrain for pipe laying.