Water-conducting household appliance with a device for customising a washing program for removing soiling from items being washed in the water-conducting household appliance, wherein the device for customising a washing program for removing soiling from items being washed has the following: a sensor designed to acquire spectral measurement values of organic compounds in the washing water in the water-conducting household appliance, a determination unit designed to determine functional groups of the organic compounds based on the acquired spectral measurement values of the organic compounds and a customisation unit designed to customise washing parameters of a current washing program based on the determined functional groups, wherein the washing parameters have a temperature of the washing water, a type of washing agent and/or a time when the washing agent is added, wherein the sensor is designed to perform spectroscopy, wherein the spectroscopy is infrared spectroscopy, near infrared spectroscopy, Fourier transform infrared spectroscopy, electron absorption spectroscopy, microwave spectroscopy, nuclear magnetic resonance spectroscopy, mass spectroscopy or Raman spectroscopy, wherein the functional groups of proteins and/or carbohydrates can be determined, characterised in that the customisation unit is designed • to customise the washing parameters in such a manner that a cold prewash without alkalinity is performed, if the functional group of proteins is determined and/or • to customise the washing parameters in such a manner that an alkaline agent is added to the washing water and a cold prewash with alkalinity is performed, if the functional group of carbohydrates is determined and/or • to determine a gelatinisation temperature of the carbohydrates, if the functional group of carbohydrates is determined and to customise the washing parameters in such a manner that the temperature of the washing water corresponds to the gelatinisation temperature. a sensor designed to acquire spectral measurement values of organic compounds in the washing water in the water-conducting household appliance, a determination unit designed to determine functional groups of the organic compounds based on the acquired spectral measurement values of the organic compounds and a customisation unit designed to customise washing parameters of a current washing program based on the determined functional groups, wherein the washing parameters have a temperature of the washing water, a type of washing agent and/or a time when the washing agent is added, wherein the sensor is designed to perform spectroscopy, wherein the spectroscopy is infrared spectroscopy, near infrared spectroscopy, Fourier transform infrared spectroscopy, electron absorption spectroscopy, microwave spectroscopy, nuclear magnetic resonance spectroscopy, mass spectroscopy or Raman spectroscopy, wherein the functional groups of proteins and/or carbohydrates can be determined, characterised in that the customisation unit is designed • to customise the washing parameters in such a manner that a cold prewash without alkalinity is performed, if the functional group of proteins is determined and/or • to customise the washing parameters in such a manner that an alkaline agent is added to the washing water and a cold prewash with alkalinity is performed, if the functional group of carbohydrates is determined and/or • to determine a gelatinisation temperature of the carbohydrates, if the functional group of carbohydrates is determined and to customise the washing parameters in such a manner that the temperature of the washing water corresponds to the gelatinisation temperature. • to customise the washing parameters in such a manner that a cold prewash without alkalinity is performed, if the functional group of proteins is determined and/or • to customise the washing parameters in such a manner that an alkaline agent is added to the washing water and a cold prewash with alkalinity is performed, if the functional group of carbohydrates is determined and/or • to determine a gelatinisation temperature of the carbohydrates, if the functional group of carbohydrates is determined and to customise the washing parameters in such a manner that the temperature of the washing water corresponds to the gelatinisation temperature.