Household Behaviour and Energy Loss in Intermittent Water Supply Networks

Intermittent water supply (IWS) networks are a problematic reality for over one billion people. Despite their drawbacks, IWS networks persist, and projects to convert them to continuous supply often fail. Here we explore one reason such projects might fail: the energy loss associated with IWS. Under IWS, water is delivered over a shorter period, increasing flow rates and thereby increasing energy losses. Could this energy loss prevent utilities from increasing their supply durations?To explore this question, we built two IWS versions of the Modena water network in EPANET. All households were assumed to withdraw water either i) as hastily as possible or ii) as patiently as possible. Artificial tanks and emitters modelled household storage and network leakage, respectively. Artificial tanks filled quickly, mimicking hasty withdrawals. To model patient withdrawals, a flow control valve was installed upstream of the tank, distributing withdrawals evenly throughout the duration of water supply.Simulations showed that when households withdraw hastily, energy losses strictly increase as the supply continuity of the network increases. Conversely, when households withdraw water patiently, energy losses increase initially, reach at least one maximum, and then decrease as supply continuity increases. Our results suggest that since energy losses often increase as utilities increase continuity, energy loss could obstruct some utilities from increasing supply continuity and from achieving continuous supply. We also found clear evidence that network behaviour strongly depends on the hastiness of household withdrawals. We also found that when networks with patient households are supplied with ample continuity, leakage can substantially influence the energy loss. We recommend additional theoretical and field research on IWS investigate the pace at which household withdrawals occur.