The municipality of Almere is planning to develop a new carbon neutral neighbourhood. The area is located close to a treated water storage facility. By extracting enough thermal energy to provide 900 homes with energy for space heating and heating tap water, the temperature of the treated water is lowered by 1.16 °C. This could lead to an increase in the energy required to heat water for domestic purposes. The temperature of tap water is influenced by the temperature of the soil surrounding the drinking water distribution system. The rate at which the water temperature will reach the soil temperature depends on the pipe material, the pipe diameter and the flow velocity. With the help of a network model, the effect of a lower initial water temperature on every customer in Almere was determined. On average, all 75,000 connections would receive slightly cooler water. The energy to heat the extra 0.125 °C is equivalent to the energy required to heat approximately 85 homes. As the extracted thermal energy enables heating of 900 homes, the energy balance is very positive.