A single bottle can hold dozens or possibly even thousands of microscopic plastic particles.
Bottled water, which is marketed as the very essence of purity is the fastest-growing beverage market in the world, valued at $147 billion per year.
However, new research by Washington DC-based Orb Media, a non-profit journalistic enterprise, shows that a single bottle can hold dozens or possibly even thousands of microscopic plastic particles.
Tests on over 250 bottles from 11 brands reveal contamination with plastic including polypropylene, nylon, and polyethylene terephthalate (PET).
Two leading brands have confirmed that their products contain microplastic, but said the company's study significantly overstates the amount.
State University of New York which conducted tests for Orb reveal a global average of 10.4 plastic particles a litre.
Samples were taken from 19 locations in nine countries on five continents. Some bottles had effectively zero plastic, but one contained over 10,000 particles a litre. Plastic was found in 93 per cent of the samples.
''This is shocking,'' said Erik Solheim, executive director of the United Nations Environment Program, orbmedia reported. ''Please name one human being on the entire planet who wants plastic in his or her bottle.''
Meanwhile, a senior Australian researcher believes consumers should be worried by research that showed that major brands of bottled water being produced and sold all around the world contain microplastic particles.
Mark Browne, an ecologist who works with the University of New South Wales, told 9News.com.au that while more work needs to be done to extend on a world-first investigation led by US-based journalism organisation Orb Media, the findings should cause concern.
Scientists are currently not sure of the complete effect microplastics could have on the human body due to a lack of government- or industry-funded research, but it has been acknowledged that ingesting them could potentially cause inflammation and scar tissue.