Abstract: A Method for regulating the disinfection of a liquid includes a number of stages. At one stage of the said disinfection (stage 2), the activity of at least one enzyme is measured by bringing the microorganisms which may be present in the liquid into contact with a substrate capable of revealing the activity of the enzyme, this enzymatic activity being referred to as specific activity. At another stage (stage 1), prior to stage 2, there occurs measuring the activity of the same enzymes. This activity being referred to as initial activity. The next stage involves translating, for each enzyme, the specific activity and initial activity, into levels of microorganisms surviving in the liquid at stage 2 of the disinfection by means of a reference system pre-established with the aid of a sample of the liquid collected at stage 1 and then exposed to increasing doses of disinfectant.