Rationalization and experimental confirmation of an efficient method of on-line waste water quality control using a generalized monitoring parameter, have been carried out, basing on the analysis and evaluation of modern technologies for industrial waste water quality control. A version of the practical processing of information intended for implementing the broadband spectroscopy for on-line quality control of the treatable water is described, as well as the structure and an example of the scheme of waste water treating device are presented, which include the system of operational control of water quality.