Developing a Methodology for the Testing of Microplastics in Drinking Water Treatment Plants

Microplastics, generally defined as any plastic particle with a size of 1 µm – 5 mm, are becoming increasingly discussed as a contaminant of concern. They have been found throughout the environment – within the air, oceans and freshwater bodies, and more recently within water intended for human consumption, including bottled and tap water. Secondary microplastics form as a result of the breakdown of larger plastic items, whereas primary microplastics are intentionally created to be this size for use in various industries. It is thought that drinking water treatment plants act as a barrier to microplastics entering drinking water, however research in this area is limited and little is known about which treatment technologies have the greatest success in their removal. It is important to understand microplastic removal via drinking water treatment to enable tracking of microplastic particles, and to develop knowledge relating to risks to human health and the environment. No standardised procedures for the sampling, testing and reporting of microplastics have yet been implemented. This study presents the results from a preliminary investigation, testing for microplastics at various stages in one drinking water treatment plant in Northern Ireland. Microplastics were found in 100% of samples tested, with fibres being the most common microplastic type recovered. Future work will include compositional analysis of microplastics and an assessment of microplastics in varying source waters. This will improve knowledge relating to the origins of microplastics found in water systems and will aid the development of future management practices.