Overview of residual disinfection practice by European water suppliers

This paper summarises the current approach to disinfection in different European countries, and describes some of the factors that will drive change. Historically, the wide diversity in water resource availability and supply infrastructure across the Continent, as well as disinfection philosophy, have all influenced disinfection practice. However, in the future new EU regulatory standards for disinfection byproducts and customer pressure for improved water taste, will also have a growing impact. The paper reviews the fundamental principles of disinfection, both at source and in the distribution network, and highlights the critical issue of balancing microbial risk against achievement of low disinfection by-product levels and acceptable tastes for customers, New technology is facilitating moves towards low or even zero disinfectant residuals, However, whilst the goal of zero network residuals and high standards of microbiological safety has already been achieved in some parts of Europe, in many supply systems this will only be possible at significant cost.