In the majority of the European Community, the assessment of odours and flavours in water supplies are carried out only by sensory analysis. Consequently it is essential for institutes and water companies to use the most accurate method in evaluating odour and flavour in drinking water. Until recently, most of the European countries had their own method or national Standard. Due to the requirements for odour and flavour in EC Directive 80/778 on drinking water quality, applicable throughout Europe, there was a need to standardise their method of evaluation. At the time, no ISO Standard for flavour and odour existed. Moreover, since the materials intended for contact with drinking water must not induce organoleptic problems, manufacturers of pipes, fittings and coatings are also concerned in a standardization. This paper presents the state of the art for flavour and odour evaluation in European countries and the next European Standard for these parameters. The Standard will be based on the dilution method to obtain a threshold flavour number (TFN) and a threshold odour number (TON) of a water. The principle is to compare the successive dilutions of water samples with a reference water. Several methods can be used, for example paired and triangle test, forced and unforced choice. The Standard also includes the selection, training and calibration of panellists. This Standard was elaborated within the scope of CEN/TC 230 “Water Analysis”, and was achieved through the active participation of experts from water institutes, water companies and manufacturers of materials.