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