Why you shouldn’t be drinking water from plastic bottles, according to science

Thailand’s Phi Phi Islands look stunning in pictures – but the often reality is much different. Beautiful beaches are littered with plastic, and that inspired Sarah Sajedi to do a PhD after realising the issue with the plastic bottles on the beach were linked to consumption. So, what did she find out? 

Along with her years of experience at ERA Environmental Management Solutions, Sajedi went to Concordia University to study the risks of bottled water. Her review of more than 140 studies reveal that people swallow between 39,000 and 52,000 microplastic particles every year. Bottled water drinkers add roughly 90,000 more .

Microplastics are tiny and they can measure just a thousandth of a millimeter – and nanoplastics are even smaller. Every time they are made, stored, or heated, plastic bottles shed fragments which go straight into the body where some can slip into the bloodstream and others settle in organs. Research has found that microplastics are linked to chronic inflammation, hormonal disruption, oxidative stress, neurological problems and even cancer .

Nanoplastics can enter cells and interact with DNA and proteins, which may lead to genetic damage and long-term health effects. And this daily exposure can quietly stack up serious health risks over time. And since water bottles also carry additives, chemicals like bisphenols and phthalates can leach into the liquid, especially when the bottles face heat or have been repeatedly used .

In her research, which is published in Journal of Hazardous Materials, Sajedi identifies multiple methods researchers have used to measure nano and microplastics. She says that some researchers can detect very small particles but cannot identify their chemical composition. Others can provide details about their makeup but miss the smallest plastics .

However, since there are no consistent methods, it’s hard to compare results or create global safety standards. Bottled water is a blind spot since governments have taken steps against single-use plastics with bags, straws and packaging often face bans. There are solutions, like reusable containers, public fountains and refill stations but some researchers are also testing new biodegradable plastics .

Sajedi said: ‘Education is the most important action we can take. Drinking water from plastic bottles is fine in an emergency but it is not something that should be used in daily life. People need to understand that the issue is not acute toxicity, it is chronic toxicity’ .