This European Standard specifies quantitative methods for determining the TON and TFN of waters and also a qualitative method for determining any abnormal odour and/or flavour. It is essential that the safety remarks in Clause 5 are taken into account. Two quantitative methods are described: ? a short method applicable when either a sample has no odour and flavour or when the odour and flavour are to be compared with a specified threshold number; ? a full method applicable when the threshold number for the sample is to be determined. For both quantitative methods, two different methodologies are described: ? unforced choice in the standard; ? forced choice in Annex B. Both methods are applicable for quantifying the odour and flavour of drinking water and/or migration waters from materials in contact with waters. NOTE The choice of the quantitative or qualitative method is depending on the national regulations, and on the type of water to be assessed (raw water, distribution water, migration water ….)