Spatial analysis of water temperature in drinking water distribution systems: assessing the effectiveness of interventions for climate change adaptation

The primary function of a drinking water distribution system (DWDS) is supplying safe and reliable drinking water. The maintenance of water’s microbiological safety is one of the most critical aspects. Temperature is an important determinant of drinking water quality and cool water, besides limiting the absorption of chemicals and the microbial growth, is also more palatable. Drinking water temperature (DWT) significantly changes between the water treatment plant and the customer’s tap and the main contributing factor is the soil temperature around the distribution mains. Soil heats up/cools down the pipe wall, which transfers heat to the flowing water inside the main at a rate that depends on the pipe’s material, diameter and flow velocity. In the urban environment, green areas alternate with asphalt streets and buildings, and several underground utilities, such as district heating networks or power lines, populate the subsurface. Both ground cover and anthropogenic heat sources highly influence soil temperature. With climate change, urbanisation and energy transition it is expected that DWTs will rise. This thesis analyses the spatial distribution of DWT in the DWDS of Almere (Netherlands) focusing on the hotspots’ detection and mitigation. For this purpose, a water temperature model is implemented in EPANET-MSX and coupled with the hydraulic model of Almere’s DWDS. Once assessed the current situation in Almere’s DWDS, an extreme future climate scenario for a summer in the Netherlands is simulated. In this scenario of a 4°C-increase in air temperature it is assessed the effectiveness of a series of measures against the unwanted water warming in the DWDS, such as the change in street cover with permeable pavements, the thermal energy extraction from drinking water, pipe insulation and design of new green areas. A final mix of interventions is outlined to comply with the Dutch legislative limit of 25°C on DWT at the tap and to make the DWDS climate resilient.