Use of Personal care products (PCPs) and herbicides has highly increased during last decades. These products can reach aquatic ecosystems, both through diffuse and/or local sources, where they are detected at low concentration. Under water scarcity, products reaching the river biota may have higher concentrations, and produce extended pulses. This situation may produce chronic contamination with unknown impacts on aquatic ecosystems. Among the commonly detected PCPs, Triclosan (TCS) is used as a broad-spectrum antimicrobial in several products as toothpaste, shampoos, etc. Several studies investigating removaI rates of TCS during wastewater treatment, detected TCS in the effluents and some of them showed the persistence in river water. Triclosan was also detected in wild living fishes and in human milk. Diuron (DIU) is a well known herbicide included into the list of priority pollutants of the EU Water Framework Directive (WFD). Several studies investigated effects of these compounds on aquatic organisms in a single-specie tests, though less have focused on the biofilm community response. In particular, no previous studies investigated effect of both compounds for ecosystem services as auto-depuration capacity (P uptake) of rivers. In this talk, results of a laboratory exposure of fluvial biofilms to both compounds will be presented. The results of the study confirm the effects that higher concentration of pollutants, occurring under poor dilution, produce in the biofilm. The mode of action of the two toxicants was different. TCS mainly affected the bacterial compartment, DIU affected mostly the algal compartment. Triclosan specially effected the P uptake capacity of the biofilm, which might determine a reduction of the self-depuration capacity in the river ecosystem. These compounds further affected the biofilm structure.