Nongfu Spring, a major domestic mineral water producer, reaffirmed on Friday that its products met both national and local water safety standards, in response to a recent media allegation that its water quality was lower than tap water.

"Nongfu's product quality is far above existing national, industry and local standards," the company said in a statement posted on its official microblog on Friday.

The statement came in response to a Beijing Times newspaper's report published on Friday alleging that the standard that Nongfu followed was a local one from East China's Zhejiang Province, which is more tolerant toward the levels of certain toxic substances such as arsenic and cadmium.

Based on the local standard DB33/383-2005 that Nongfu uses, the maximum arsenic and cadmium content tolerance is double and five times respectively the levels stated in GB5749-2006 which is the current national standard for drinking water.

According to the filing of the Zhejiang quality watchdog, Nongfu is the only water producer that participated in revising the local rules back in 2005, that lifted cadmium levels from the original 0.005 milligram per liter (mg/L) to 0.01 mg/L.

Any bottled water producer must abide by the compulsory national standard and use it as a bottom line, with any breach in implementation being a violation of the country's Food Safety Law, Ma Jinya, secretary-general of China National Health Association Drinking Healthy Committee, was quoted as saying by the Beijing Times on Friday.

But it is possible that the actual water quality produced by major bottled water producers such as Nongfu is above both standards, Ma said.

"I will pay more attention when picking bottled water, but even if a standard can be seen on the label, how can I know it is the right one?" said Zhang Ning, a 38-year-old white-collar worker.

As can be seen in a supermarket, nine mineral water brands including Nongfu, Nestle and and Wahaha, show seven different standards on their labels, some of them are national, some local, and some are even the producer's own standards.

"There has been a lack of specific national standards for natural and mineral water, which has led to this chaotic situation," Xiang Jianjun, a food and beverage analyst at CIC Industry Research Center, told the Global Times on Friday.

The water quality of Nongfu Spring's major water source, Qiandao Lake in Zhejiang Province, is reportedly as Class IV - an indicator for industrial use rather than for drinking, and another of its water sources Danjiangkou Reservoir in Hubei Province is ringed by garbage.

Nongfu blamed the recent negative media reports on a plot by its rival C'estbon Food & Beverage (Shenzhen).

C'estbon issued a statement late Thursday, denying Nongfu's accusation and saying it reserves the right to pursue legal action against Nongfu.