Microplastics, plastic particles of < 5 mm, are well-known emergent pollutants, ubiquitous in all ecosystems on the planet. They are considered a global threat, being aquatic ecosystems the most affected by them and inland freshwater ecosystems less studied in regards to this matter. When microplastics enter the ecosystems, they produce a wide range of impacts on biodiversity, ecosystem functions, production and animal health. Microplastics enter these ecosystems mainly due to the human activity, for this reason, in this research, the comparison of the microplastic content of sixteen wetlands from Spain and United Kingdom with two different land uses in their catchment basin was carried out: agricultural-livestock and forestry. In the process, two filter sizes were compared to demonstrate which one is more suitable for these studies, which is a smaller pore size filter. Microplastics were found in fifteen wetlands, although no significant difference was found between the ponds of the United Kingdom, nor comparing them with the Spanish. However, in Spain it was evident that agriculture, especially olive groves, causes an outstanding microplastic pollution in wetlands, likely due to the intensification of this cultivation, more use of plastic and more waste caused by olive farmers and higher erosion of the soil. Lastly, some measure to minimize microplastics inputs are suggested.