*Article* **Network Capacity Assessment and Increase in Systems with Intermittent Water Supply**

#### **Amilkar E. Ilaya-Ayza \*, Enrique Campbell, Rafael Pérez-García and Joaquín Izquierdo**

FluIng-IMM, Universitat Politècnica de València, Camino de Vera s/n Edif. 5C, Spain; encamgo1@upv.es (E.C.); rperez@upv.es (R.P.-G.); jizquier@upv.es (J.I.)

**\*** Correspondence: amilay@upv.es; Tel.: +34-693-918-718

Academic Editor: Helena Ramos

Received: 3 January 2016; Accepted: 28 March 2016; Published: 31 March 2016

**Abstract:** Water supply systems have been facing many challenges in recent decades due to the potential effects of climate change and rapid population growth. Water systems need to expand because of demographic growth. Therefore, evaluating and increasing system capacity is crucial. Specifically, we analyze network capacity as one of the main features of a system. When the network capacity starts to decrease, there is a risk that continuous supply will become intermittent. This paper discusses how network expansion carried out throughout the network life span typically reduces network capacity, thus transforming a system originally designed to work with continuous supply into a system with intermittent supply. A method is proposed to expand the network capacity in an environment of economic scarcity through a greedy algorithm that enables the definition of a schedule for pipe modification stages, and thus efficiently expands the network capacity. This method is, at the same time, an important step in the process of changing a water system from intermittent back to continuous supply—an achievement that remains one of the main challenges related to water and health in developing countries.

**Keywords:** water network expansion; water network capacity; intermittent water supply; theoretical maximum flow; system setting curve
