Drinking water temperatures are expected to increase in the Netherlands due to climate change and the installation of district heating networks as part of the energy transition. To determine effective measures to prevent undesirable temperature increases in drinking water, a model was developed. This model describes the temperature in the drinking water distribution network as a result of the transfer of heat from the climate and above and underground heat sources through the soil. The model consists of two coupled applications. The extended soil temperature model (STM+) describes the soil temperatures using a two-dimensional finite element method that includes a drinking water pipe and two hot water pipes coupled with a micrometeorology model. The extended water temperature model (WTM+) describes the drinking water temperature as a function of the surrounding soil temperature (the boundary temperature resulting from the STM+), the thermal sphere of influence where the drinking water temperature influences the soil temperature, and the hydraulics in the drinking water network. Both models are validated with field measurements. This study describes the WTM+. Previous models did not consider the cooling effect of the drinking water on the surrounding soil, which led to an overestimation of the boundary temperature and how quickly the drinking water temperature reaches this boundary temperature. The field measurements show the improved accuracy of the WTM+ when considering one to two times the radius of the drinking water pipe as the thermal sphere of influence around the pipe.

Large water distribution networks require efficient use of their resources. One of the ways to become more efficient is to reduce the energy consumption due to pumping systems [1] [2]. In the European context the city of Milan has a large water supply system for 1.3 million inhabitants and around 4.0 million commuters, which is supplied entirely by 26 pumping stations. The system currently supplies its ∼50,000 customers with 103 pumps which are actively operated during the day [3]. In previous years a pump scheduling algorithm has been proposed to the utility for a Pressure Management Zone (PMZ) in the south of the city named Abbiategrasso containing only 4 pumps [4] [5]. However, it is of the interest for the utility to extend the analysis to the whole system [6] [7]. For that reason it is necessary to perform a proper pump scheduling. The solution proposed here, is a Multi-Objective Optimization (MOO) for the energy consumption reduction of the whole Water Distribution Network (WDN) using an EPANET model of the whole network. Results show that there is room for improvement of energy and pressure management in the system. The solution presented here can be applied to other utilities with similar challenges.