Microplastics (MPs) awareness has been growing particularly after several alarming reports about “garbage patches” in the world. Plastics do not biodegrade in any meaningful way and, up to now, only a small percentage of plastic waste is recycled, being all the rest dumped in landfills, incinerated or simply not collected. The distribution of MPs within the water ecosystem depends on particle density and size and environmental characteristics, such as winds and currents. In the present study, different Portuguese industrial effluents were analysed and characterised to determine which MPs in the treated water released from wastewater treatment plants (WWTP), predominate and contribute the most to the environmental contamination of aquifers which, eventually, will end up in the coast of Continental Portugal. Overall, this work suggests strategies for MPs analysis in WWTP, thus allowing mapping of the different types of MPs prevalent in Portugal. The establishment of such database will enable the creation of reliable laboratory models to test new and green removal processes, based on the flocculation by, for instance, bio-based flocculants.