The presence in natural watercourses of different types of emerging contaminants (including stimulants and antibiotics) from different sources constitutes a serious environmental issue. The problem is aggravated in regions where water is scarce and its reuse should form part of its integrated cycle. The removal of these contaminants, so that the water may be reused, is currently one of the most widely studied issues in the field of wastewater treatment. Within this context, the present paper addresses the removal of different contaminants (caffeine, theobromine, theophylline, amoxicillin, and penicillin G). The chosen treatment was the use of reverse osmosis membranes, which were installed at the outlet of the secondary settling tank of the wastewater treatment plant (WWTP) in Medina Sidonia (SW Spain), carrying out sampling in the feed, reject and permeate streams over a period of 72 h. DOW-FILMTEC BW30-2540 membranes were used for this purpose, operating at a pressure of 15 bar. The emerging contaminants were analysed by Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS). The applied treatments allowed a contaminant-free permeate to be obtained with the required quality for its reuse. This technique achieved 100% removal of the contaminants without signs of membrane deterioration after running the 72 h test.