Drinking water temperature model for urban environments validated with measurements from real-life distribution networks

Abstract

The Dutch drinking water sector distributes treated drinking water without a disinfecting residual. Among many other microbiological safety measures, Dutch water utilities are legally obliged to distribute drinking water to the customers’ tap at a maximum temperature of 25 °C. Ongoing urbanization, climate change, and subsurface infrastructure intensification related to the energy transition pose a growing risk to meet this requirement.Previous research at KWR has shown that the temperature of drinking water converges to the temperature of the surrounding soil that, in turn, is influenced by weather conditions and the presence of anthropogenic heat sources, such as electric power distribution stations and district heating pipes. During a hot summer, cool drinking water reaches the soil temperature within hours. The rate of warming up depends on hydraulic conditions, dimensional and thermal properties, and a delaying effect caused by the continuous supply of drinking water that cools down the surrounding soil.KWR has developed numerical tools to predict the temperature of distributed drinking water in the presence of subsurface heat sources and fluctuating weather conditions. These tools can be used to assess the impact of climate change and the urban environment on drinking water temperatures and investigate the optimized design of distribution networks and the urban environment.Our contribution describes the validation of the numerical model using drinking water temperatures measured in a real-life Dutch DWDS. The case study concerns Ø300 mm pipes in the city of Leeuwarden (Vitens drinking water company). We discuss the results in the context of two additional case studies that compare model predictions and temperature measurements in a Ø100 mm drinking water distribution network and a Ø160 mm single pipe. Finally, we discuss future applications that can improve codes of practice regarding the organization of subsurface infrastructure; a central point of attention is the installation of drinking water and district heating pipes at safe distances.