Boiling, filtering water can remove up to 90% of microplastics: study

Boiling and filtering tap water can drastically reduce the level of plastic particles in it, a study by China-based research team published Wednesday said.

Scientists from the Guangzhou Medical University and Jinan University conducted a study in which they observed the effect of boiling mineral-rich water, to see if it could lead to reduced human intake of nano/microplastics (NMPs).

The researchers took multiple samples of tap water from the Guangzhou region, contaminated with varying levels of NMPs, which were then boiled for five minutes and cooled for 10.

They found that boiling hard water -- water richer in dissolved calcium and magnesium -- yields calcium carbonate, which ensnares polystyrene, polyethylene and polypropylene NMPs. The chalky residue that trapped the tiny plastic particles was then removed from the water by pouring the water through a standard coffee filter.

For water samples containing around 180 milligrams per liter of calcium carbonate, boiling and filtering it removed 84 percent of the NMPs. The figure rose to 90 percent for harder water samples containing around 300 milligrams per liter of the mineral.

Even in softer water samples containing less than 60 mg per liter of calcium carbonate, boiling and filtering removed 25 percent of the nano and microplastics.

"This simple boiling-water strategy can 'decontaminate' NMPs from household tap water and has the potential for harmlessly alleviating human intake of NMPs through water consumption," the researchers wrote.

They noted that because water quality varies across the globe, the effectiveness of this practice may vary from region to region. “Nonetheless, our results have ratified a highly feasible strategy to reduce human NMP exposure and established the foundation for further investigations with a much larger number of samples," they said.

The study was published in Environmental Science & Technology Letters.

While boiling water is suggested to be effective measure of removing plastic particles, one is advised to do it in a glass or stainless steel container. Boiling water in plastic, which can dissolve at high temperatures, releases bisphenol and antimony, leading to adverse health effects.