Italian legislation (Article 13 of Legislative Decree 31/2001) provides for the possibility of establishing derogations from chemical parametric values for drinking water set by EU legislation (Council Directive 98/83/EC), if the supply of drinking water cannot be maintained by any other reasonable means. A derogation is possible only after obtaining a specific authorization and must be limited to the shortest time possible. This paper presents the history of derogations granted in Italy and the case of arsenic and nickel in Piedmont. From 2003 to 2009, 13 regions requested a derogation (Campania, Emilia Romagna, Latium, Lombardy, Marche, Piedmont, Apulia, Sardinia, Sicily, Tuscany, Trentino Alto Adige, Umbria, Venetia) at different times and for a total of 13 parameters. In 2012, tap water provided to almost one million Italians in 112 municipalities of three regions (Latium, Tuscany and Campania), did not comply with the legal limits for the following parameters: arsenic, boron and fluorides. Currently, in the Piedmont region there are no derogations from the maximum permitted concentrations of contaminants in drinking water. In the past derogations have been applied for the nickel parameter (years 2006-2007) and from the arsenic parameter (years 2006-2008).