Investigating the amounts of microplastics and their sampling methods in the tap water distribution network: a systematic review and meta-analysis

Abstract

Abstract: Identifying microplastics (MPs) in tap water attracted much attention, recently. Present study was aimed to systematically review MPs contamination and characteristics in tap water. All techniques used for sampling, processing and analyzing of MPs in tap water were also assessed. Furthermore, characteristics of MPs, including the abundance, type, color and shape were summarized. Various data bases including Web of Science, PubMed, Science direct, Scopus, Springer, and MDPI was searched to find published articles up to January 2025. The occurrence of MPs in tap water was Meta-analyzed using the random effect model. A total of 6100 articles were found, of which 43 were included in the systematic review process. The results indicated that the pooled mean of MPs in tap water is 56.98 P/L. Manual sampling with a sample volume of less than 1 liter has mainly used, and microscopic, Raman, and Fourier-transform infrared spectroscopy (FTIR) were the common methods of extracting and identifying of MPs. The most abundant polymer identified was Polyethylene (PE), followed by Polyethylene terephthalate (PET) and polypropylene (PP). The fibers and fragments were the dominant forms of MPs found in water. The lack of harmonized protocol and the difficulty of validating MP analysis methods in tap water have led to different and sometimes contradictory data, which makes it difficult and unreliable to compare the results. The results of this systematic review will help to establish a comprehensive protocol and provide a standardized and harmonized method for MP analysis in tap water. Key Words: Microplastics, drinking water, tap water, sampling, identification, characterization