Quantifying the effect of distance between drinking water and district heating mains on drinking water temperature

“During transport and distribution the drinking water temperature can increase due to relatively high soil temperatures surrounding the drinking water distribution networks (DWDN). A drinking water temperature below 25 °C at the tap is required to meet Legionella prevention standards and/or drinking water standards [1]. Soil temperatures are affected by climatic factors and anthropogenic heat sources above and below ground level [2]. With climate change, urbanisation and the energy transition, which in the Netherlands in particular comes with an expected increased number of district heating networks (DHN), the urban subsurface will heat up even further. Currently the drinking water temperature at the tap sporadically exceeds the norm, but with these developments more exceedance is expected [1].
The Dutch drinking water companies are expecting a lot of district heating networks (DHN) to be installed in the coming years as part of the energy transition. There is a need to determine the minimum distance that is required between DWDN and DHN, to ensure the DHN does not lead to too high drinking water temperatures. There is limited space in the underground with all the urban infrastructure that’s already in place. Therefore, the distance between DHN and DWDS will have to be trade-off between available space and water quality, with a small (but not zero) influence of the DHN on the drinking water temperature.”

(Citation: Blokker, E.J.M., Pan, Q. – Quantifying the effect of distance between drinking water and district heating mains on drinking water temperature – 19th International Computing & Control for the Water Industry Conference, 4-7 September 2023)