AbstractFor a speedy solution to the problem of water resources preservation it is necessary at present to enhance the level of research aimed at establishing a system of classification of water pollutants. Control of the state of the environment must be based on wide use of achievements by different branches of scientific research. Watching the change of the biological component of the biosphere (biomonitoring) is to ascertain the response by susceptible biotic forms to environmental pollutant influence. Microorganisms are among the organismus which are most susceptible to environment influence. Test culture responses to influences from different pollutants were evaluated by building mathematical models. The principles worked out in drawing up response models could be used to develop classification systems.