Temperatures in drinking water distribution systems: quantifying measures to limit water quality effects

“In the Netherlands, the drinking water is distributed without disinfectant residual. According to the Dutch Drinking Water Directive the temperature of the drinking water at the customers’ tap is not allowed to exceed 25 ºC. The reason is that at higher temperatures regrowth of micro- organisms, such as Legionella, may occur. Occasionally (0.03%), samples at the tap do exceed this limit and with higher outside temperatures the exceedance increases. With global warming, the limit of 25 ºC may be exceeded more often. Dutch Water Companies are interested in measures that may reduce the temperature at the tap or that restrict the negative consequences of the higher drinking water temperature.
The purpose of this paper is to study the effectiveness of different measures based on a model that predicts the temperature of the drinking water and microbial evolution in the distribution network from weather data. Modelling the temperature change in the drinking water distribution system provides insight into the most important parameters in this process. Moreover, it contributes to assess the consequences of all temperature related processes in the distribution network.”

(Citaat: Blokker, E.J.M., Pieterse-Quirijns, E.J. – Temperatures in drinking water distribution systems: quantifying measures to limit water quality effects – IWA World Congres on Water, Climate and Energy, Dublin 13-18 May 2012)