Bottled water is often perceived as clean and free of contaminants compared to tap water, but University of Otago researchers believe water quality results should be printed on the label.
Dr Tim Chambers, of the Department of Public Health, Wellington, says that amidst growing health concerns associated with nitrate contamination, increased reporting of water quality is required.
“There is growing epidemiological evidence linking nitrate contamination to adverse health outcomes including adverse birth outcomes and several cancers. Health concerns may drive consumers towards bottled water, however, nitrate levels in bottled water are not readily available,” he says.
Along with colleagues from Otago and Victoria University of Wellington, Dr Chambers analysed the nitrate levels in samples from 10 popular still water brands.
The study, published in the Australian and New Zealand Journal of Public Health, found all brands had low nitrate levels.
While the researchers say they were pleased with the results, they have concerns about how difficult it was to obtain information about the quality of bottled water.
Dr Chambers says bottled water companies are required to test for key contaminants to ensure their water complies with national drinking water standards. However, they are not required to publicly disclose this information, which is important for consumers to make informed decisions and for public health surveillance of water quality.
“It is possible that concentrations of some contaminants could be higher than tap water or above levels linked with adverse health outcomes. For example, international studies have observed associations between nitrate and adverse health outcomes at levels far below the current drinking water standard,” he says.
“We believe water quality results need to be publicly assessible. First, by introducing reporting of water quality for some key determinants on the product label as done in some European countries. Second, publication of the full suite of chemical testing results online, as two companies in this research already practice.”
A change to the Food Act to introduce mandatory reporting requirements would ensure the entire industry complied with best practice, Dr Chambers said.
This information is not only important now but will potentially be more important in coming years, he says.
“There has been a rapid agricultural intensification in some of the areas our major bottled water companies operate. While it is reassuring to see low levels of nitrate in these products, it is possible the high level of leaching could threaten some of these supplies in the future.”