A Graph-Theory Based PRV Placement Algorithm for Reducing Water Age in Water Distribution Systems

Water age is the time it takes for water to travel through a distribution system and reach the consumer. Generally, there is a tradeoff between water pressure and water age in a water distribution system – higher pressure results in higher flow velocity, meaning shorter travelling time for the water, while lower pressure leads to slower flow and thus higher water age. Low pressure is a desired objective in a distribution system, as it reduces the physical stress on its components and minimizes water losses in an event of a leak. Low water age is a desired objective as well, as water quality worsens when water age increases. The problem of trying to minimize both of those objectives is a common problem in water distribution systems operation. This paper introduces an algorithm for pressure reducing valves (PRVs) placement for reducing water age in a water distribution system. The algorithm is based on graph-theory elements and uses EPANET 2.2 for analysis. The method is demonstrated on two small scale examples.