The Consumer Council of Hong Kong has issued an apology for saying that a product of Nongfu Spring, the Chinese mainland's largest bottled water company, has a substance at the highest level set by the European Union. The council re-evaluated it as a five-star, or top-rated, product.

In a statement on Thursday, the council also said that after receiving a lawyer's letter from Nongfu Spring on Tuesday, it immediately conducted in-depth research and met with the company's representatives.

Nongfu Spring's actions came after the council published a report on Monday, detailing the results of safety tests on 30 samples of widely consumed bottled water products, including Chinese and foreign brands. The tests found the bromate levels of the bottled water of Nongfu Spring hit the maximum limit set by the European Union.

Bromate, a byproduct formed in the disinfection process, has potential health risks to human bodies when consumed in excess amounts, and can cause nausea, diarrhea, vomiting and abdominal pain, the council said.

The World Health Organization has set the upper limit of bromate content in drinking water at 10 micrograms per liter. Bottled water containing bromate levels below this limit does not pose a threat to health.

"After meeting with Nongfu Spring, we understood that the product of Nongfu Spring is neither natural mineral water nor purified water, but natural drinking water, and the company's safety standard is based on the standard of the Chinese mainland," the council said.

"In this regard, we classified the sample as an independent category of natural drinking water and re-evaluated it. We apologize for the misunderstanding caused by the discrepancy in sample classification," it said in the statement.

Although products from different origins generally use local quality standards as indicators, the council conducted comparative testing and used international standards for evaluation to protect consumer rights. The bromate level in the natural drinking water of Nongfu Spring is 3 micrograms per liter, far below the EU standard, the council said.

The council further said the 30 samples it collected came from different origins such as Hong Kong, the Chinese mainland, Japan, South Korea, France, Spain and Australia. And 29 samples were from the categories of distilled water, purified water and natural mineral water, while the sample of Nongfu Spring was labeled as natural drinking water.

Considering the four mineral contents indicated on its ingredients list are similar to those found in natural mineral water, the staff members of the council classified Nongfu Spring as natural mineral water based on the product name.

Nongfu Spring said on Thursday that it has received the clarification by the council, and the test results fully demonstrated that Nongfu Spring products comply with relevant standards and can be safely consumed.

"The bromate level of 3 micrograms per liter won't cause hidden troubles to human bodies, as stated by the council, and consumers may approach this matter rationally," said Zhu Danpeng, an independent food and beverage industry analyst.

Last year, Nongfu Spring achieved sales revenue of 42.67 billion yuan ($5.88 billion), up 28.4 percent year-on-year, which generated a net profit of 12.08 billion yuan, up 42.2 percent year-on-year, according to its annual financial report.