© 2020 The Authors Understanding source elements of the ocean plastic crisis is key to effective pollution reduction management and policy. The ubiquity of microplastic (MP) fibres in the oceans is considered to derive primarily from clothing fibres released in grey water. Microplastic fibres degraded from widely flushed personal care textile products (wet wipes and sanitary towels) have not been clearly identified in aquatic systems to date. Unregulated personal hygiene and sanitary product labelling fails to identify textile materials. This study demonstrated that white MP fibres in sediments adjacent to a wastewater treatment plant (WWTP) are comparable with white fibres from sewage-related waste and commercially available consumer sanitary products. Commercially available non-flushable wipes are manufactured from either polyethylene terephthalate (PET), polypropylene (PP), or a combination of PET and cellulose. Fifty percent of brands labelled flushable that were tested were comprised of a mixture of PET and cellulose and the remainder of cellulose alone. Sanitary towels are made from PP, PE, or a combination of high-density polyethylene (HDPE) and PP. The accumulation of large quantities of washed-up sewage-related macro-debris (including wet wipes and sanitary towels) intermingled with seaweed biomass adjacent to the WWTP was associated with a combined sewer overflow. Microplastic fibres extracted from this waste were similar to those extracted from intertidal sediments in close proximity to the WWTP over a ten-month period. In comparison, fibres extracted from locations spatially removed from the WWTP were primarily comprised of ABS, PP and polystyrene. The results confirm that wet wipes and sanitary towels flushed down toilets are an underestimated source of white MP fibres in the environment. Given the global distribution and projected growth of the non-woven textile industry, there is a need for increased public awareness of MP pollution in the marine environment from the inappropriate disposal of sanitary products down the toilet, instead of diversion to alternative land-based waste management.