A baseline study on the prevalence of microplastics in South African drinking water: from source to distribution

Abstract

Due to the worldwide increasing prevalence of microplastics in the aquatic environment, this study aimed to perform a screening of the  source and drinking water of South Africa’s largest bulk drinking water supplier to determine the extent to which microplastics occur in  the water. Source water samples, samples immediately after treatment, and samples in the distribution network (Johannesburg,   Mabopane, Garankua and Pelindaba) were analysed. Microplastics concentrations in the source water ranged from 0.24 to 1.47  particles/L, immediately after treatment from 0.56 to 0.9 particles/L, and in the distribution network from 0.26 to 0.88 particles/L. Most of  the microplastics found in the water were classified as ‘fragments’ and a few as ‘fibres’. The control sample (indicating contamination  during sample preparation and analysis) showed 0.34 particles/L, which was higher than some of the samples taken, indicating very low  microplastics concentrations in these samples. Little evidence was found that the drinking water treatment processes reduced the  number of microplastics from the source to the final treated water. No evidence could be found that the pipes in the distribution network  contribute to microplastics in the tap water. The most frequently found polymer in the samples was rubber. Based on mass,  however, as a function of particle size and polymer density, ethylene-vinyl-acetate (a polymer commonly used as foam in sporting  equipment and flip-flops) comprised 54% of the microplastics and polyethylene (standard and chlorinated) 25%.