Application of the European Water Framework Directive requires Member States to have better understanding of the quality of surface waters in order to improve knowledge of priority pollutants. Xenobiotics in urban receiving waters are an emerging concern. This study proposes a screening campaign of laurylalkylbenzene sulfonates in a separated sewer system. An analytical method by solid-phase extraction and liquid chromatography coupled with mass spectrometry detection was developed providing satisfactory detection and quantification limits. Ten sites and seven types of waters (wastewaters, treated wastewaters, ground water, rainwaters, roof collected waters, runoff waters and carwash wastewaters) were investigated over one year in Toulouse (France) using quantitative monitoring. Ground, rain and roof collected water concentrations are similar to treated wastewater levels. Run-off water was the most polluted and impacted the aquatic environment. Washing stations were responsible for 75% of the LAS load in stormwaters. The wastewater treatment plant reduced laurylalkylbenzene sulfonates concentrations by 90% before discharge into the environment. The results showed that laurylalkylbenzene sulfonates concentrations were variable over time and space in all urban water compartments. No correlation between laurylalkylbenzene sulfonates concentrations and global water pollution parameters was observed.