Equality in Unrestricted Intermittent Water Supply Networks: Conceptual Model

Up to a billion people receive drinking water intermittently, sometimes for just a few hours per week. Improving water quality and reducing inequality in these supply networks can be difficult because operational details and the configuration and condition of pipes in these networks are often uncertain. This can make it challenging to model these water networks using traditional, deterministic hydraulic models that rely on detailed information about each pipe, its diameter, and its roughness. To mitigate this challenge, this paper explores the performance of a simple, generalized, pressure-dependent model of intermittent water supply networks that does not rely on detailed information. To ensure this model has some relevance to traditional modeling approaches, the new model was validated by comparing its performance to three benchmark networks with unrestricted demands modeled by EPANET. Using the new model, we showed that consumers close to the source of supply almost always received a higher fraction of their desired water demand than those further away. Increasing supply pressure did little to reduce water inequality but could increase the total amount of water supplied. Pipes that flow to higher elevations worsened inequality among consumers in this pressure-dependent, unrestricted demand model. Efforts to reduce inequality may benefit from a focus on consumers at higher elevations. Restricting demand of users close to the source of supply may also free up water for downstream users.