Disclosed is a washing system capable of detecting a level of contamination of a laundry tub by executing a big data, an artificial intelligence (AI) algorithm and/or a machine learning algorithm in a 5G environment connected for things Internet. The washing system capable of detecting a level of contamination of a laundry tub according to one embodiment of the present disclosure includes a composite sensor for detecting a level of contamination of a laundry tub, a washing machine controller that receives a digital signal from the composite sensor to determine a level of contamination of the laundry tub, and a server communicating with the washing machine. The washing machine controller or the server learns AI model with the training data set through a machine learning algorithm in order to predict a progressing degree of contamination of the laundry tub.